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Package spanner provides a client for reading and writing to Cloud Spanner databases. See the packages under admin for clients that operate on databases and instances.
See https://cloud.google.com/spanner/docs/getting-started/go/ for an introduction to Cloud Spanner and additional help on using this API.
See https://godoc.org/cloud.google.com/go for authentication, timeouts, connection pooling and similar aspects of this package.
Creating a Client
To start working with this package, create a client that refers to the database of interest:
ctx := context.Background() client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D") if err != nil { // TODO: Handle error. } defer client.Close()
Remember to close the client after use to free up the sessions in the session pool.
To use an emulator with this library, you can set the SPANNER_EMULATOR_HOST environment variable to the address at which your emulator is running. This will send requests to that address instead of to Cloud Spanner. You can then create and use a client as usual:
// Set SPANNER_EMULATOR_HOST environment variable. err := os.Setenv("SPANNER_EMULATOR_HOST", "localhost:9010") if err != nil { // TODO: Handle error. } // Create client as usual. client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D") if err != nil { // TODO: Handle error. }
Simple Reads and Writes
Two Client methods, Apply and Single, work well for simple reads and writes. As a quick introduction, here we write a new row to the database and read it back:
_, err := client.Apply(ctx, []*spanner.Mutation{ spanner.Insert("Users", []string{"name", "email"}, []interface{}{"alice", "a@example.com"})}) if err != nil { // TODO: Handle error. } row, err := client.Single().ReadRow(ctx, "Users", spanner.Key{"alice"}, []string{"email"}) if err != nil { // TODO: Handle error. }
All the methods used above are discussed in more detail below.
Keys
Every Cloud Spanner row has a unique key, composed of one or more columns. Construct keys with a literal of type Key:
key1 := spanner.Key{"alice"}
KeyRanges
The keys of a Cloud Spanner table are ordered. You can specify ranges of keys using the KeyRange type:
kr1 := spanner.KeyRange{Start: key1, End: key2}
By default, a KeyRange includes its start key but not its end key. Use the Kind field to specify other boundary conditions:
// include both keys kr2 := spanner.KeyRange{Start: key1, End: key2, Kind: spanner.ClosedClosed}
KeySets
A KeySet represents a set of keys. A single Key or KeyRange can act as a KeySet. Use the KeySets function to build the union of several KeySets:
ks1 := spanner.KeySets(key1, key2, kr1, kr2)
AllKeys returns a KeySet that refers to all the keys in a table:
ks2 := spanner.AllKeys()
Transactions
All Cloud Spanner reads and writes occur inside transactions. There are two types of transactions, read-only and read-write. Read-only transactions cannot change the database, do not acquire locks, and may access either the current database state or states in the past. Read-write transactions can read the database before writing to it, and always apply to the most recent database state.
Single Reads
The simplest and fastest transaction is a ReadOnlyTransaction that supports a single read operation. Use Client.Single to create such a transaction. You can chain the call to Single with a call to a Read method.
When you only want one row whose key you know, use ReadRow. Provide the table name, key, and the columns you want to read:
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
Read multiple rows with the Read method. It takes a table name, KeySet, and list of columns:
iter := client.Single().Read(ctx, "Accounts", keyset1, columns)
Read returns a RowIterator. You can call the Do method on the iterator and pass a callback:
err := iter.Do(func(row *Row) error { // TODO: use row return nil })
RowIterator also follows the standard pattern for the Google Cloud Client Libraries:
defer iter.Stop() for { row, err := iter.Next() if err == iterator.Done { break } if err != nil { // TODO: Handle error. } // TODO: use row }
Always call Stop when you finish using an iterator this way, whether or not you iterate to the end. (Failing to call Stop could lead you to exhaust the database's session quota.)
To read rows with an index, use ReadUsingIndex.
Statements
The most general form of reading uses SQL statements. Construct a Statement with NewStatement, setting any parameters using the Statement's Params map:
stmt := spanner.NewStatement("SELECT First, Last FROM SINGERS WHERE Last >= @start") stmt.Params["start"] = "Dylan"
You can also construct a Statement directly with a struct literal, providing your own map of parameters.
Use the Query method to run the statement and obtain an iterator:
iter := client.Single().Query(ctx, stmt)
Rows
Once you have a Row, via an iterator or a call to ReadRow, you can extract column values in several ways. Pass in a pointer to a Go variable of the appropriate type when you extract a value.
You can extract by column position or name:
err := row.Column(0, &name) err = row.ColumnByName("balance", &balance)
You can extract all the columns at once:
err = row.Columns(&name, &balance)
Or you can define a Go struct that corresponds to your columns, and extract into that:
var s struct { Name string; Balance int64 } err = row.ToStruct(&s)
For Cloud Spanner columns that may contain NULL, use one of the NullXXX types, like NullString:
var ns spanner.NullString if err := row.Column(0, &ns); err != nil { // TODO: Handle error. } if ns.Valid { fmt.Println(ns.StringVal) } else { fmt.Println("column is NULL") }
Multiple Reads
To perform more than one read in a transaction, use ReadOnlyTransaction:
txn := client.ReadOnlyTransaction() defer txn.Close() iter := txn.Query(ctx, stmt1) // ... iter = txn.Query(ctx, stmt2) // ...
You must call Close when you are done with the transaction.
Timestamps and Timestamp Bounds
Cloud Spanner read-only transactions conceptually perform all their reads at a single moment in time, called the transaction's read timestamp. Once a read has started, you can call ReadOnlyTransaction's Timestamp method to obtain the read timestamp.
By default, a transaction will pick the most recent time (a time where all previously committed transactions are visible) for its reads. This provides the freshest data, but may involve some delay. You can often get a quicker response if you are willing to tolerate "stale" data. You can control the read timestamp selected by a transaction by calling the WithTimestampBound method on the transaction before using it. For example, to perform a query on data that is at most one minute stale, use
client.Single(). WithTimestampBound(spanner.MaxStaleness(1*time.Minute)). Query(ctx, stmt)
See the documentation of TimestampBound for more details.
Mutations
To write values to a Cloud Spanner database, construct a Mutation. The spanner package has functions for inserting, updating and deleting rows. Except for the Delete methods, which take a Key or KeyRange, each mutation-building function comes in three varieties.
One takes lists of columns and values along with the table name:
m1 := spanner.Insert("Users", []string{"name", "email"}, []interface{}{"alice", "a@example.com"})
One takes a map from column names to values:
m2 := spanner.InsertMap("Users", map[string]interface{}{ "name": "alice", "email": "a@example.com", })
And the third accepts a struct value, and determines the columns from the struct field names:
type User struct { Name, Email string } u := User{Name: "alice", Email: "a@example.com"} m3, err := spanner.InsertStruct("Users", u)
Writes
To apply a list of mutations to the database, use Apply:
_, err := client.Apply(ctx, []*spanner.Mutation{m1, m2, m3})
If you need to read before writing in a single transaction, use a ReadWriteTransaction. ReadWriteTransactions may be aborted automatically by the backend and need to be retried. You pass in a function to ReadWriteTransaction, and the client will handle the retries automatically. Use the transaction's BufferWrite method to buffer mutations, which will all be executed at the end of the transaction:
_, err := client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error { var balance int64 row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"}) if err != nil { // The transaction function will be called again if the error code // of this error is Aborted. The backend may automatically abort // any read/write transaction if it detects a deadlock or other // problems. return err } if err := row.Column(0, &balance); err != nil { return err } if balance <= 10 { return errors.New("insufficient funds in account") } balance -= 10 m := spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance}) // The buffered mutation will be committed. If the commit // fails with an Aborted error, this function will be called // again. return txn.BufferWrite([]*spanner.Mutation{m}) })
Structs
Cloud Spanner STRUCT (aka STRUCT) values (https://cloud.google.com/spanner/docs/data-types#struct-type) can be represented by a Go struct value.
A proto StructType is built from the field types and field tag information of
the Go struct. If a field in the struct type definition has a
"spanner:<field_name>" tag, then the value of the "spanner" key in the tag is
used as the name for that field in the built StructType, otherwise the field
name in the struct definition is used. To specify a field with an empty field
name in a Cloud Spanner STRUCT type, use the spanner:""
tag annotation against
the corresponding field in the Go struct's type definition.
A STRUCT value can contain STRUCT-typed and Array-of-STRUCT typed fields and these can be specified using named struct-typed and []struct-typed fields inside a Go struct. However, embedded struct fields are not allowed. Unexported struct fields are ignored.
NULL STRUCT values in Cloud Spanner are typed. A nil pointer to a Go struct value can be used to specify a NULL STRUCT value of the corresponding StructType. Nil and empty slices of a Go STRUCT type can be used to specify NULL and empty array values respectively of the corresponding StructType. A slice of pointers to a Go struct type can be used to specify an array of NULL-able STRUCT values.
DML and Partitioned DML
Spanner supports DML statements like INSERT, UPDATE and DELETE. Use ReadWriteTransaction.Update to run DML statements. It returns the number of rows affected. (You can call use ReadWriteTransaction.Query with a DML statement. The first call to Next on the resulting RowIterator will return iterator.Done, and the RowCount field of the iterator will hold the number of affected rows.)
For large databases, it may be more efficient to partition the DML statement. Use client.PartitionedUpdate to run a DML statement in this way. Not all DML statements can be partitioned.
Tracing
This client has been instrumented to use OpenCensus tracing (http://opencensus.io). To enable tracing, see "Enabling Tracing for a Program" at https://godoc.org/go.opencensus.io/trace. OpenCensus tracing requires Go 1.8 or higher.
Constants
Scope, AdminScope
const (
// Scope is the scope for Cloud Spanner Data API.
Scope = "https://www.googleapis.com/auth/spanner.data"
// AdminScope is the scope for Cloud Spanner Admin APIs.
AdminScope = "https://www.googleapis.com/auth/spanner.admin"
)
NumericPrecisionDigits, NumericScaleDigits
const (
// NumericPrecisionDigits is the maximum number of digits in a NUMERIC
// value.
NumericPrecisionDigits = 38
// NumericScaleDigits is the maximum number of digits after the decimal
// point in a NUMERIC value.
NumericScaleDigits = 9
)
OtInstrumentationScope
const OtInstrumentationScope = "cloud.google.com/go"
OtInstrumentationScope is the instrumentation name that will be associated with the emitted telemetry.
Variables
OpenSessionCount, OpenSessionCountView, MaxAllowedSessionsCount, MaxAllowedSessionsCountView, SessionsCount, SessionsCountView, MaxInUseSessionsCount, MaxInUseSessionsCountView, GetSessionTimeoutsCount, GetSessionTimeoutsCountView, AcquiredSessionsCount, AcquiredSessionsCountView, ReleasedSessionsCount, ReleasedSessionsCountView, GFELatency, GFELatencyView, GFEHeaderMissingCount, GFEHeaderMissingCountView
var (
OpenSessionCount = stats.Int64(
statsPrefix+"open_session_count",
"Number of sessions currently opened",
stats.UnitDimensionless,
)
OpenSessionCountView = &view.View{
Measure: OpenSessionCount,
Aggregation: view.LastValue(),
TagKeys: tagCommonKeys,
}
MaxAllowedSessionsCount = stats.Int64(
statsPrefix+"max_allowed_sessions",
"The maximum number of sessions allowed. Configurable by the user.",
stats.UnitDimensionless,
)
MaxAllowedSessionsCountView = &view.View{
Measure: MaxAllowedSessionsCount,
Aggregation: view.LastValue(),
TagKeys: tagCommonKeys,
}
SessionsCount = stats.Int64(
statsPrefix+"num_sessions_in_pool",
"The number of sessions currently in use.",
stats.UnitDimensionless,
)
SessionsCountView = &view.View{
Measure: SessionsCount,
Aggregation: view.LastValue(),
TagKeys: append(tagCommonKeys, tagKeyType),
}
MaxInUseSessionsCount = stats.Int64(
statsPrefix+"max_in_use_sessions",
"The maximum number of sessions in use during the last 10 minute interval.",
stats.UnitDimensionless,
)
MaxInUseSessionsCountView = &view.View{
Measure: MaxInUseSessionsCount,
Aggregation: view.LastValue(),
TagKeys: tagCommonKeys,
}
GetSessionTimeoutsCount = stats.Int64(
statsPrefix+"get_session_timeouts",
"The number of get sessions timeouts due to pool exhaustion.",
stats.UnitDimensionless,
)
GetSessionTimeoutsCountView = &view.View{
Measure: GetSessionTimeoutsCount,
Aggregation: view.Count(),
TagKeys: tagCommonKeys,
}
AcquiredSessionsCount = stats.Int64(
statsPrefix+"num_acquired_sessions",
"The number of sessions acquired from the session pool.",
stats.UnitDimensionless,
)
AcquiredSessionsCountView = &view.View{
Measure: AcquiredSessionsCount,
Aggregation: view.Count(),
TagKeys: tagCommonKeys,
}
ReleasedSessionsCount = stats.Int64(
statsPrefix+"num_released_sessions",
"The number of sessions released by the user and pool maintainer.",
stats.UnitDimensionless,
)
ReleasedSessionsCountView = &view.View{
Measure: ReleasedSessionsCount,
Aggregation: view.Count(),
TagKeys: tagCommonKeys,
}
GFELatency = stats.Int64(
statsPrefix+"gfe_latency",
"Latency between Google's network receiving an RPC and reading back the first byte of the response",
stats.UnitMilliseconds,
)
GFELatencyView = &view.View{
Name: "cloud.google.com/go/spanner/gfe_latency",
Measure: GFELatency,
Description: "Latency between Google's network receives an RPC and reads back the first byte of the response",
Aggregation: view.Distribution(0.0, 0.01, 0.05, 0.1, 0.3, 0.6, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 13.0,
16.0, 20.0, 25.0, 30.0, 40.0, 50.0, 65.0, 80.0, 100.0, 130.0, 160.0, 200.0, 250.0,
300.0, 400.0, 500.0, 650.0, 800.0, 1000.0, 2000.0, 5000.0, 10000.0, 20000.0, 50000.0,
100000.0),
TagKeys: append(tagCommonKeys, tagKeyMethod),
}
GFEHeaderMissingCount = stats.Int64(
statsPrefix+"gfe_header_missing_count",
"" /* 128 byte string literal not displayed */,
stats.UnitDimensionless,
)
GFEHeaderMissingCountView = &view.View{
Name: "cloud.google.com/go/spanner/gfe_header_missing_count",
Measure: GFEHeaderMissingCount,
Description: "" /* 128 byte string literal not displayed */,
Aggregation: view.Count(),
TagKeys: append(tagCommonKeys, tagKeyMethod),
}
)
CommitTimestamp
var (
// CommitTimestamp is a special value used to tell Cloud Spanner to insert
// the commit timestamp of the transaction into a column. It can be used in
// a Mutation, or directly used in InsertStruct or InsertMap. See
// ExampleCommitTimestamp. This is just a placeholder and the actual value
// stored in this variable has no meaning.
CommitTimestamp = commitTimestamp
)
DefaultRetryBackoff
var DefaultRetryBackoff = gax.Backoff{
Initial: 20 * time.Millisecond,
Max: 32 * time.Second,
Multiplier: 1.3,
}
DefaultRetryBackoff is used for retryers as a fallback value when the server did not return any retry information.
DefaultSessionPoolConfig
var DefaultSessionPoolConfig = SessionPoolConfig{
MinOpened: 100,
MaxOpened: numChannels * 100,
MaxBurst: 10,
WriteSessions: 0.2,
HealthCheckWorkers: 10,
HealthCheckInterval: healthCheckIntervalMins * time.Minute,
InactiveTransactionRemovalOptions: InactiveTransactionRemovalOptions{
ActionOnInactiveTransaction: Warn,
// contains filtered or unexported fields
},
// contains filtered or unexported fields
}
DefaultSessionPoolConfig is the default configuration for the session pool that will be used for a Spanner client, unless the user supplies a specific session pool config.
ErrRowNotFound
Functions
func DisableGfeLatencyAndHeaderMissingCountViews (deprecated)
func DisableGfeLatencyAndHeaderMissingCountViews()
DisableGfeLatencyAndHeaderMissingCountViews disables GFEHeaderMissingCount and GFELatency metric
Deprecated: OpenCensus project is deprecated. Use OpenTelemetry for capturing metrics.
func EnableGfeHeaderMissingCountView (deprecated)
func EnableGfeHeaderMissingCountView() error
EnableGfeHeaderMissingCountView enables GFEHeaderMissingCount metric
Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get GfeHeaderMissingCount metrics through OpenTelemetry instrumentation.
func EnableGfeLatencyAndHeaderMissingCountViews (deprecated)
func EnableGfeLatencyAndHeaderMissingCountViews() error
EnableGfeLatencyAndHeaderMissingCountViews enables GFEHeaderMissingCount and GFELatency metric
Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get GfeLatency and GfeHeaderMissingCount metrics through OpenTelemetry instrumentation.
func EnableGfeLatencyView (deprecated)
func EnableGfeLatencyView() error
EnableGfeLatencyView enables GFELatency metric
Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get GfeLatency metrics through OpenTelemetry instrumentation.
func EnableOpenTelemetryMetrics
func EnableOpenTelemetryMetrics()
EnableOpenTelemetryMetrics enables OpenTelemetery metrics
func EnableStatViews (deprecated)
func EnableStatViews() error
EnableStatViews enables all views of metrics relate to session management.
Deprecated: OpenCensus project is deprecated. Use EnableOpenTelemetryMetrics to get Session metrics through OpenTelemetry instrumentation.
func ErrCode
ErrCode extracts the canonical error code from a Go error.
func ErrDesc
ErrDesc extracts the Cloud Spanner error description from a Go error.
func ExtractRetryDelay
ExtractRetryDelay extracts retry backoff from a *spanner.Error if present.
func IsOpenTelemetryMetricsEnabled
func IsOpenTelemetryMetricsEnabled() bool
IsOpenTelemetryMetricsEnabled tells whether OpenTelemtery metrics is enabled or not.
func NumericString
NumericString returns a string representing a *big.Rat in a format compatible with Spanner SQL. It returns a floating-point literal with 9 digits after the decimal point.
func SelectAll
func SelectAll(rows rowIterator, destination interface{}, options ...DecodeOptions) error
SelectAll iterates all rows to the end. After iterating it closes the rows and propagates any errors that could pop up with destination slice partially filled. It expects that destination should be a slice. For each row, it scans data and appends it to the destination slice. SelectAll supports both types of slices: slice of pointers and slice of structs or primitives by value, for example:
type Singer struct {
ID string
Name string
}
var singersByPtr []*Singer
var singersByValue []Singer
Both singersByPtr and singersByValue are valid destinations for SelectAll function.
Add the option spanner.WithLenient()
to instruct SelectAll to ignore additional columns in the rows that are not present in the destination struct.
example:
var singersByPtr []*Singer
err := spanner.SelectAll(row, &singersByPtr, spanner.WithLenient())
func ToSpannerError
ToSpannerError converts a general Go error to *spanner.Error. If the given error is already a *spanner.Error, the original error will be returned.
Spanner Errors are normally created by the Spanner client library from the returned APIError of a RPC. This method can also be used to create Spanner errors for use in tests. The recommended way to create test errors is calling this method with a status error, e.g. ToSpannerError(status.New(codes.NotFound, "Table not found").Err())
func UseNumberWithJSONDecoderEncoder
func UseNumberWithJSONDecoderEncoder(useNumber bool)
UseNumberWithJSONDecoderEncoder specifies whether Cloud Spanner JSON numbers are decoded as Number (preserving precision) or float64 (risking loss). Defaults to the same behavior as the standard Go library, which means decoding to float64. Call this method to enable lossless precision. NOTE 1: Calling this method affects the behavior of all clients created by this library, both existing and future instances. NOTE 2: This method sets a global variable that is used by the client to encode/decode JSON numbers. Access to the global variable is not synchronized. You should only call this method when there are no goroutines encoding/decoding Cloud Spanner JSON values. It is recommended to only call this method during the initialization of your application, and preferably before you create any Cloud Spanner clients, and/or in tests when there are no queries being executed.
ActionOnInactiveTransactionKind
type ActionOnInactiveTransactionKind int
ActionOnInactiveTransactionKind describes the kind of action taken when there are inactive transactions.
NoAction, Warn, Close, WarnAndClose
const (
// NoAction action does not perform any action on inactive transactions.
NoAction ActionOnInactiveTransactionKind
// Warn action logs inactive transactions. Any inactive transaction gets logged only once.
Warn
// Close action closes inactive transactions without logging.
Close
// WarnAndClose action logs and closes the inactive transactions.
WarnAndClose
)
ApplyOption
type ApplyOption func(*applyOption)
An ApplyOption is an optional argument to Apply.
func ApplyAtLeastOnce
func ApplyAtLeastOnce() ApplyOption
ApplyAtLeastOnce returns an ApplyOption that removes replay protection.
With this option, Apply may attempt to apply mutations more than once; if the mutations are not idempotent, this may lead to a failure being reported when the mutation was applied more than once. For example, an insert may fail with ALREADY_EXISTS even though the row did not exist before Apply was called. For this reason, most users of the library will prefer not to use this option. However, ApplyAtLeastOnce requires only a single RPC, whereas Apply's default replay protection may require an additional RPC. So this option may be appropriate for latency sensitive and/or high throughput blind writing.
func ApplyCommitOptions
func ApplyCommitOptions(co CommitOptions) ApplyOption
ApplyCommitOptions returns an ApplyOption that sets the commit options to use for the commit operation.
func ExcludeTxnFromChangeStreams
func ExcludeTxnFromChangeStreams() ApplyOption
ExcludeTxnFromChangeStreams returns an ApplyOptions that sets whether to exclude recording this commit operation from allowed tracking change streams.
func Priority
func Priority(priority sppb.RequestOptions_Priority) ApplyOption
Priority returns an ApplyOptions that sets the RPC priority to use for the commit operation.
func TransactionTag
func TransactionTag(tag string) ApplyOption
TransactionTag returns an ApplyOption that will include the given tag as a transaction tag for a write-only transaction.
BatchReadOnlyTransaction
type BatchReadOnlyTransaction struct {
ReadOnlyTransaction
ID BatchReadOnlyTransactionID
}
BatchReadOnlyTransaction is a ReadOnlyTransaction that allows for exporting arbitrarily large amounts of data from Cloud Spanner databases. BatchReadOnlyTransaction partitions a read/query request. Read/query request can then be executed independently over each partition while observing the same snapshot of the database. BatchReadOnlyTransaction can also be shared across multiple clients by passing around the BatchReadOnlyTransactionID and then recreating the transaction using Client.BatchReadOnlyTransactionFromID.
Note: if a client is used only to run partitions, you can create it using a ClientConfig with both MinOpened and MaxIdle set to zero to avoid creating unnecessary sessions. You can also avoid excess gRPC channels by setting ClientConfig.NumChannels to the number of concurrently active BatchReadOnlyTransactions you expect to have.
func (*BatchReadOnlyTransaction) AnalyzeQuery
func (t *BatchReadOnlyTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)
AnalyzeQuery returns the query plan for statement.
func (*BatchReadOnlyTransaction) Cleanup
func (t *BatchReadOnlyTransaction) Cleanup(ctx context.Context)
Cleanup cleans up all the resources used by this transaction and makes it unusable. Once this method is invoked, the transaction is no longer usable anywhere, including other clients/processes with which this transaction was shared.
Calling Cleanup is optional, but recommended. If Cleanup is not called, the transaction's resources will be freed when the session expires on the backend and is deleted. For more information about recycled sessions, see https://cloud.google.com/spanner/docs/sessions.
func (*BatchReadOnlyTransaction) Close
func (t *BatchReadOnlyTransaction) Close()
Close marks the txn as closed.
func (*BatchReadOnlyTransaction) Execute
func (t *BatchReadOnlyTransaction) Execute(ctx context.Context, p *Partition) *RowIterator
Execute runs a single Partition obtained from PartitionRead or PartitionQuery.
func (*BatchReadOnlyTransaction) PartitionQuery
func (t *BatchReadOnlyTransaction) PartitionQuery(ctx context.Context, statement Statement, opt PartitionOptions) ([]*Partition, error)
PartitionQuery returns a list of Partitions that can be used to execute a query against the database.
func (*BatchReadOnlyTransaction) PartitionQueryWithOptions
func (t *BatchReadOnlyTransaction) PartitionQueryWithOptions(ctx context.Context, statement Statement, opt PartitionOptions, qOpts QueryOptions) ([]*Partition, error)
PartitionQueryWithOptions returns a list of Partitions that can be used to execute a query against the database. The sql query execution will be optimized based on the given query options.
func (*BatchReadOnlyTransaction) PartitionRead
func (t *BatchReadOnlyTransaction) PartitionRead(ctx context.Context, table string, keys KeySet, columns []string, opt PartitionOptions) ([]*Partition, error)
PartitionRead returns a list of Partitions that can be used to read rows from the database. These partitions can be executed across multiple processes, even across different machines. The partition size and count hints can be configured using PartitionOptions.
func (*BatchReadOnlyTransaction) PartitionReadUsingIndex
func (t *BatchReadOnlyTransaction) PartitionReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string, opt PartitionOptions) ([]*Partition, error)
PartitionReadUsingIndex returns a list of Partitions that can be used to read rows from the database using an index.
func (*BatchReadOnlyTransaction) PartitionReadUsingIndexWithOptions
func (t *BatchReadOnlyTransaction) PartitionReadUsingIndexWithOptions(ctx context.Context, table, index string, keys KeySet, columns []string, opt PartitionOptions, readOptions ReadOptions) ([]*Partition, error)
PartitionReadUsingIndexWithOptions returns a list of Partitions that can be used to read rows from the database using an index. Pass a ReadOptions to modify the read operation.
func (*BatchReadOnlyTransaction) PartitionReadWithOptions
func (t *BatchReadOnlyTransaction) PartitionReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opt PartitionOptions, readOptions ReadOptions) ([]*Partition, error)
PartitionReadWithOptions returns a list of Partitions that can be used to read rows from the database. These partitions can be executed across multiple processes, even across different machines. The partition size and count hints can be configured using PartitionOptions. Pass a ReadOptions to modify the read operation.
func (*BatchReadOnlyTransaction) Query
func (t *BatchReadOnlyTransaction) Query(ctx context.Context, statement Statement) *RowIterator
Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.
Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.
func (*BatchReadOnlyTransaction) QueryWithOptions
func (t *BatchReadOnlyTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator
QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.
func (*BatchReadOnlyTransaction) QueryWithStats
func (t *BatchReadOnlyTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator
QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.
func (*BatchReadOnlyTransaction) Read
func (t *BatchReadOnlyTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator
Read returns a RowIterator for reading multiple rows from the database.
func (*BatchReadOnlyTransaction) ReadRow
func (t *BatchReadOnlyTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)
ReadRow reads a single row from the database.
If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*BatchReadOnlyTransaction) ReadRowUsingIndex
func (t *BatchReadOnlyTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)
ReadRowUsingIndex reads a single row from the database using an index.
If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.
func (*BatchReadOnlyTransaction) ReadRowWithOptions
func (t *BatchReadOnlyTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)
ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.
If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*BatchReadOnlyTransaction) ReadUsingIndex
func (t *BatchReadOnlyTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)
ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.
func (*BatchReadOnlyTransaction) ReadWithOptions
func (t *BatchReadOnlyTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)
ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.
BatchReadOnlyTransactionID
type BatchReadOnlyTransactionID struct {
// contains filtered or unexported fields
}
BatchReadOnlyTransactionID is a unique identifier for a BatchReadOnlyTransaction. It can be used to re-create a BatchReadOnlyTransaction on a different machine or process by calling Client.BatchReadOnlyTransactionFromID.
func (BatchReadOnlyTransactionID) MarshalBinary
func (tid BatchReadOnlyTransactionID) MarshalBinary() (data []byte, err error)
MarshalBinary implements BinaryMarshaler.
func (*BatchReadOnlyTransactionID) UnmarshalBinary
func (tid *BatchReadOnlyTransactionID) UnmarshalBinary(data []byte) error
UnmarshalBinary implements BinaryUnmarshaler.
BatchWriteOptions
type BatchWriteOptions struct {
// Priority is the RPC priority to use for this request.
Priority sppb.RequestOptions_Priority
// The transaction tag to use for this request.
TransactionTag string
// If excludeTxnFromChangeStreams == true, modifications from all transactions
// in this batch write request will not be recorded in allowed tracking
// change treams with DDL option allow_txn_exclusion=true.
ExcludeTxnFromChangeStreams bool
}
BatchWriteOptions provides options for a BatchWriteRequest.
BatchWriteResponseIterator
type BatchWriteResponseIterator struct {
// contains filtered or unexported fields
}
BatchWriteResponseIterator is an iterator over BatchWriteResponse structures returned from BatchWrite RPC.
func (*BatchWriteResponseIterator) Do
func (r *BatchWriteResponseIterator) Do(f func(r *sppb.BatchWriteResponse) error) error
Do calls the provided function once in sequence for each item in the iteration. If the function returns a non-nil error, Do immediately returns that error.
If there are no items in the iterator, Do will return nil without calling the provided function.
Do always calls Stop on the iterator.
func (*BatchWriteResponseIterator) Next
func (r *BatchWriteResponseIterator) Next() (*sppb.BatchWriteResponse, error)
Next returns the next result. Its second return value is iterator.Done if there are no more results. Once Next returns Done, all subsequent calls will return Done.
func (*BatchWriteResponseIterator) Stop
func (r *BatchWriteResponseIterator) Stop()
Stop terminates the iteration. It should be called after you finish using the iterator.
Client
type Client struct {
// contains filtered or unexported fields
}
Client is a client for reading and writing data to a Cloud Spanner database. A client is safe to use concurrently, except for its Close method.
func NewClient
NewClient creates a client to a database. A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID. It uses a default configuration.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
func main() {
ctx := context.Background()
const myDB = "projects/my-project/instances/my-instance/database/my-db"
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
_ = client // TODO: Use client.
}
func NewClientWithConfig
func NewClientWithConfig(ctx context.Context, database string, config ClientConfig, opts ...option.ClientOption) (c *Client, err error)
NewClientWithConfig creates a client to a database. A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
func main() {
ctx := context.Background()
const myDB = "projects/my-project/instances/my-instance/database/my-db"
client, err := spanner.NewClientWithConfig(ctx, myDB, spanner.ClientConfig{
NumChannels: 10,
})
if err != nil {
// TODO: Handle error.
}
_ = client // TODO: Use client.
client.Close() // Close client when done.
}
func NewMultiEndpointClient
func NewMultiEndpointClient(ctx context.Context, database string, gmeCfg *grpcgcp.GCPMultiEndpointOptions, opts ...option.ClientOption) (*Client, *grpcgcp.GCPMultiEndpoint, error)
NewMultiEndpointClient is the same as NewMultiEndpointClientWithConfig with the default client configuration.
A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID.
func NewMultiEndpointClientWithConfig
func NewMultiEndpointClientWithConfig(ctx context.Context, database string, config ClientConfig, gmeCfg *grpcgcp.GCPMultiEndpointOptions, opts ...option.ClientOption) (c *Client, gme *grpcgcp.GCPMultiEndpoint, err error)
NewMultiEndpointClientWithConfig creates a client to a database using GCPMultiEndpoint.
The purposes of GCPMultiEndpoint are:
- Fallback to an alternative endpoint (host:port) when the original endpoint is completely unavailable.
- Be able to route a Cloud Spanner call to a specific group of endpoints.
- Be able to reconfigure endpoints in runtime.
The GRPCgcpConfig and DialFunc in the GCPMultiEndpointOptions are optional and will be configured automatically.
For GCPMultiEndpoint the number of channels is configured via MaxSize of the ChannelPool config in the GRPCgcpConfig.
The GCPMultiEndpoint returned can be used to update the endpoints in runtime.
A valid database name has the form projects/PROJECT_ID/instances/INSTANCE_ID/databases/DATABASE_ID.
func (*Client) Apply
func (c *Client) Apply(ctx context.Context, ms []*Mutation, opts ...ApplyOption) (commitTimestamp time.Time, err error)
Apply applies a list of mutations atomically to the database.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
m := spanner.Update("Users", []string{"name", "email"}, []interface{}{"alice", "a@example.com"})
_, err = client.Apply(ctx, []*spanner.Mutation{m})
if err != nil {
// TODO: Handle error.
}
}
func (*Client) BatchReadOnlyTransaction
func (c *Client) BatchReadOnlyTransaction(ctx context.Context, tb TimestampBound) (*BatchReadOnlyTransaction, error)
BatchReadOnlyTransaction returns a BatchReadOnlyTransaction that can be used for partitioned reads or queries from a snapshot of the database. This is useful in batch processing pipelines where one wants to divide the work of reading from the database across multiple machines.
Note: This transaction does not use the underlying session pool but creates a new session each time, and the session is reused across clients.
You should call Close() after the txn is no longer needed on local client, and call Cleanup() when the txn is finished for all clients, to free the session.
Example
package main
import (
"context"
"sync"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
var (
client *spanner.Client
txn *spanner.BatchReadOnlyTransaction
err error
)
if client, err = spanner.NewClient(ctx, myDB); err != nil {
// TODO: Handle error.
}
defer client.Close()
if txn, err = client.BatchReadOnlyTransaction(ctx, spanner.StrongRead()); err != nil {
// TODO: Handle error.
}
defer txn.Close()
// Singer represents the elements in a row from the Singers table.
type Singer struct {
SingerID int64
FirstName string
LastName string
SingerInfo []byte
}
stmt := spanner.Statement{SQL: "SELECT * FROM Singers;"}
partitions, err := txn.PartitionQuery(ctx, stmt, spanner.PartitionOptions{})
if err != nil {
// TODO: Handle error.
}
// Note: here we use multiple goroutines, but you should use separate
// processes/machines.
wg := sync.WaitGroup{}
for i, p := range partitions {
wg.Add(1)
go func(i int, p *spanner.Partition) {
defer wg.Done()
iter := txn.Execute(ctx, p)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
} else if err != nil {
// TODO: Handle error.
}
var s Singer
if err := row.ToStruct(&s); err != nil {
// TODO: Handle error.
}
_ = s // TODO: Process the row.
}
}(i, p)
}
wg.Wait()
}
func (*Client) BatchReadOnlyTransactionFromID
func (c *Client) BatchReadOnlyTransactionFromID(tid BatchReadOnlyTransactionID) *BatchReadOnlyTransaction
BatchReadOnlyTransactionFromID reconstruct a BatchReadOnlyTransaction from BatchReadOnlyTransactionID
func (*Client) BatchWrite
func (c *Client) BatchWrite(ctx context.Context, mgs []*MutationGroup) *BatchWriteResponseIterator
BatchWrite applies a list of mutation groups in a collection of efficient transactions. The mutation groups are applied non-atomically in an unspecified order and thus, they must be independent of each other. Partial failure is possible, i.e., some mutation groups may have been applied successfully, while some may have failed. The results of individual batches are streamed into the response as the batches are applied.
BatchWrite requests are not replay protected, meaning that each mutation group may be applied more than once. Replays of non-idempotent mutations may have undesirable effects. For example, replays of an insert mutation may produce an already exists error or if you use generated or commit timestamp-based keys, it may result in additional rows being added to the mutation's table. We recommend structuring your mutation groups to be idempotent to avoid this issue.
func (*Client) BatchWriteWithOptions
func (c *Client) BatchWriteWithOptions(ctx context.Context, mgs []*MutationGroup, opts BatchWriteOptions) *BatchWriteResponseIterator
BatchWriteWithOptions is same as BatchWrite. It accepts additional options to customize the request.
func (*Client) ClientID
ClientID returns the id of the Client. This is not recommended for customer applications and used internally for testing.
func (*Client) Close
func (c *Client) Close()
Close closes the client.
func (*Client) DatabaseName
DatabaseName returns the full name of a database, e.g., "projects/spanner-cloud-test/instances/foo/databases/foodb".
func (*Client) PartitionedUpdate
func (c *Client) PartitionedUpdate(ctx context.Context, statement Statement) (count int64, err error)
PartitionedUpdate executes a DML statement in parallel across the database, using separate, internal transactions that commit independently. The DML statement must be fully partitionable: it must be expressible as the union of many statements each of which accesses only a single row of the table. The statement should also be idempotent, because it may be applied more than once.
PartitionedUpdate returns an estimated count of the number of rows affected. The actual number of affected rows may be greater than the estimate.
func (*Client) PartitionedUpdateWithOptions
func (c *Client) PartitionedUpdateWithOptions(ctx context.Context, statement Statement, opts QueryOptions) (count int64, err error)
PartitionedUpdateWithOptions executes a DML statement in parallel across the database, using separate, internal transactions that commit independently. The sql query execution will be optimized based on the given query options.
func (*Client) ReadOnlyTransaction
func (c *Client) ReadOnlyTransaction() *ReadOnlyTransaction
ReadOnlyTransaction returns a ReadOnlyTransaction that can be used for multiple reads from the database. You must call Close() when the ReadOnlyTransaction is no longer needed to release resources on the server.
ReadOnlyTransaction will use a strong TimestampBound by default. Use ReadOnlyTransaction.WithTimestampBound to specify a different TimestampBound. A non-strong bound can be used to reduce latency, or "time-travel" to prior versions of the database, see the documentation of TimestampBound for details.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
t := client.ReadOnlyTransaction()
defer t.Close()
// TODO: Read with t using Read, ReadRow, ReadUsingIndex, or Query.
}
func (*Client) ReadWriteTransaction
func (c *Client) ReadWriteTransaction(ctx context.Context, f func(context.Context, *ReadWriteTransaction) error) (commitTimestamp time.Time, err error)
ReadWriteTransaction executes a read-write transaction, with retries as necessary.
The function f will be called one or more times. It must not maintain any state between calls.
If the transaction cannot be committed or if f returns an ABORTED error, ReadWriteTransaction will call f again. It will continue to call f until the transaction can be committed or the Context times out or is cancelled. If f returns an error other than ABORTED, ReadWriteTransaction will abort the transaction and return the error.
To limit the number of retries, set a deadline on the Context rather than using a fixed limit on the number of attempts. ReadWriteTransaction will retry as needed until that deadline is met.
See https://godoc.org/cloud.google.com/go/spanner#ReadWriteTransaction for more details.
Example
package main
import (
"context"
"errors"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
var balance int64
row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
if err != nil {
// This function will be called again if this is an IsAborted error.
return err
}
if err := row.Column(0, &balance); err != nil {
return err
}
if balance <= 10 {
return errors.New("insufficient funds in account")
}
balance -= 10
m := spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance})
// The buffered mutation will be committed. If the commit fails with an
// IsAborted error, this function will be called again.
return txn.BufferWrite([]*spanner.Mutation{m})
})
if err != nil {
// TODO: Handle error.
}
}
func (*Client) ReadWriteTransactionWithOptions
func (c *Client) ReadWriteTransactionWithOptions(ctx context.Context, f func(context.Context, *ReadWriteTransaction) error, options TransactionOptions) (resp CommitResponse, err error)
ReadWriteTransactionWithOptions executes a read-write transaction with configurable options, with retries as necessary.
ReadWriteTransactionWithOptions is a configurable ReadWriteTransaction.
See https://godoc.org/cloud.google.com/go/spanner#ReadWriteTransaction for more details.
func (*Client) Single
func (c *Client) Single() *ReadOnlyTransaction
Single provides a read-only snapshot transaction optimized for the case where only a single read or query is needed. This is more efficient than using ReadOnlyTransaction() for a single read or query.
Single will use a strong TimestampBound by default. Use ReadOnlyTransaction.WithTimestampBound to specify a different TimestampBound. A non-strong bound can be used to reduce latency, or "time-travel" to prior versions of the database, see the documentation of TimestampBound for details.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
_ = iter // TODO: iterate using Next or Do.
}
ClientConfig
type ClientConfig struct {
// NumChannels is the number of gRPC channels.
// If zero, a reasonable default is used based on the execution environment.
//
// Deprecated: The Spanner client now uses a pool of gRPC connections. Use
// option.WithGRPCConnectionPool(numConns) instead to specify the number of
// connections the client should use. The client will default to a
// reasonable default if this option is not specified.
NumChannels int
// SessionPoolConfig is the configuration for session pool.
SessionPoolConfig
// SessionLabels for the sessions created by this client.
// See https://cloud.google.com/spanner/docs/reference/rpc/google.spanner.v1#session
// for more info.
SessionLabels map[string]string
// QueryOptions is the configuration for executing a sql query.
QueryOptions QueryOptions
// ReadOptions is the configuration for reading rows from a database
ReadOptions ReadOptions
// ApplyOptions is the configuration for applying
ApplyOptions []ApplyOption
// TransactionOptions is the configuration for a transaction.
TransactionOptions TransactionOptions
// BatchWriteOptions is the configuration for a BatchWrite request.
BatchWriteOptions BatchWriteOptions
// CallOptions is the configuration for providing custom retry settings that
// override the default values.
CallOptions *vkit.CallOptions
// UserAgent is the prefix to the user agent header. This is used to supply information
// such as application name or partner tool.
//
// Internal Use Only: This field is for internal tracking purpose only,
// setting the value for this config is not required.
//
// Recommended format: ``application-or-tool-ID/major.minor.version``.
UserAgent string
// DatabaseRole specifies the role to be assumed for all operations on the
// database by this client.
DatabaseRole string
// DisableRouteToLeader specifies if all the requests of type read-write and PDML
// need to be routed to the leader region.
//
// Default: false
DisableRouteToLeader bool
// Logger is the logger to use for this client. If it is nil, all logging
// will be directed to the standard logger.
Logger *log.Logger
//
// Sets the compression to use for all gRPC calls. The compressor must be a valid name.
// This will enable compression both from the client to the
// server and from the server to the client.
//
// Supported values are:
// gzip: Enable gzip compression
// identity: Disable compression
//
// Default: identity
Compression string
// BatchTimeout specifies the timeout for a batch of sessions managed sessionClient.
BatchTimeout time.Duration
// ClientConfig options used to set the DirectedReadOptions for all ReadRequests
// and ExecuteSqlRequests for the Client which indicate which replicas or regions
// should be used for non-transactional reads or queries.
DirectedReadOptions *sppb.DirectedReadOptions
OpenTelemetryMeterProvider metric.MeterProvider
}
ClientConfig has configurations for the client.
CommitOptions
CommitOptions provides options for committing a transaction in a database.
CommitResponse
type CommitResponse struct {
// CommitTs is the commit time for a transaction.
CommitTs time.Time
// CommitStats is the commit statistics for a transaction.
CommitStats *sppb.CommitResponse_CommitStats
}
CommitResponse provides a response of a transaction commit in a database.
DecodeOptions
type DecodeOptions interface {
Apply(s *decodeSetting)
}
DecodeOptions is the interface to change decode struct settings
func WithLenient
func WithLenient() DecodeOptions
WithLenient returns a DecodeOptions that allows decoding into a struct with missing fields in database.
Decoder
type Decoder interface {
DecodeSpanner(input interface{}) error
}
Decoder is the interface implemented by a custom type that can be decoded from a supported type by Spanner. A code example:
type customField struct {
Prefix string
Suffix string
}
// Convert a string to a customField value
func (cf *customField) DecodeSpanner(val interface{}) (err error) {
strVal, ok := val.(string)
if !ok {
return fmt.Errorf("failed to decode customField: %v", val)
}
s := strings.Split(strVal, "-")
if len(s) > 1 {
cf.Prefix = s[0]
cf.Suffix = s[1]
}
return nil
}
Encoder
type Encoder interface {
EncodeSpanner() (interface{}, error)
}
Encoder is the interface implemented by a custom type that can be encoded to a supported type by Spanner. A code example:
type customField struct {
Prefix string
Suffix string
}
// Convert a customField value to a string
func (cf customField) EncodeSpanner() (interface{}, error) {
var b bytes.Buffer
b.WriteString(cf.Prefix)
b.WriteString("-")
b.WriteString(cf.Suffix)
return b.String(), nil
}
Error (deprecated)
type Error struct {
// Code is the canonical error code for describing the nature of a
// particular error.
//
// Deprecated: The error code should be extracted from the wrapped error by
// calling ErrCode(err error). This field will be removed in a future
// release.
Code codes.Code
// Desc explains more details of the error.
Desc string
// contains filtered or unexported fields
}
Error is the structured error returned by Cloud Spanner client.
Deprecated: Unwrap any error that is returned by the Spanner client as an APIError to access the error details. Do not try to convert the error to the spanner.Error struct, as that struct may be removed in a future release.
Example: var apiErr *apierror.APIError _, err := spanner.NewClient(context.Background()) errors.As(err, &apiErr)
func (*Error) Error (deprecated)
Error implements error.Error.
func (*Error) GRPCStatus (deprecated)
GRPCStatus returns the corresponding gRPC Status of this Spanner error.
This allows the error to be converted to a gRPC status using
status.Convert(error)
.
func (*Error) Unwrap (deprecated)
Unwrap returns the wrapped error (if any).
GenericColumnValue
GenericColumnValue represents the generic encoded value and type of the column. See google.spanner.v1.ResultSet proto for details. This can be useful for proxying query results when the result types are not known in advance.
If you populate a GenericColumnValue from a row using Row.Column or related methods, do not modify the contents of Type and Value.
func (GenericColumnValue) Decode
func (v GenericColumnValue) Decode(ptr interface{}) error
Decode decodes a GenericColumnValue. The ptr argument should be a pointer to a Go value that can accept v.
Example
package main
import (
"fmt"
"cloud.google.com/go/spanner"
sppb "cloud.google.com/go/spanner/apiv1/spannerpb"
)
func main() {
// In real applications, rows can be retrieved by methods like client.Single().ReadRow().
row, err := spanner.NewRow([]string{"intCol", "strCol"}, []interface{}{42, "my-text"})
if err != nil {
// TODO: Handle error.
}
for i := 0; i < row.Size(); i++ {
var col spanner.GenericColumnValue
if err := row.Column(i, &col); err != nil {
// TODO: Handle error.
}
switch col.Type.Code {
case sppb.TypeCode_INT64:
var v int64
if err := col.Decode(&v); err != nil {
// TODO: Handle error.
}
fmt.Println("int", v)
case sppb.TypeCode_STRING:
var v string
if err := col.Decode(&v); err != nil {
// TODO: Handle error.
}
fmt.Println("string", v)
}
}
}
InactiveTransactionRemovalOptions
type InactiveTransactionRemovalOptions struct {
// ActionOnInactiveTransaction is the configuration to choose action for inactive transactions.
// It can be one of Warn, Close, WarnAndClose.
ActionOnInactiveTransaction ActionOnInactiveTransactionKind
// contains filtered or unexported fields
}
InactiveTransactionRemovalOptions has configurations for action on long-running transactions.
Key
type Key []interface{}
A Key can be either a Cloud Spanner row's primary key or a secondary index key. It is essentially an interface{} array, which represents a set of Cloud Spanner columns. A Key can be used as:
- A primary key which uniquely identifies a Cloud Spanner row.
- A secondary index key which maps to a set of Cloud Spanner rows indexed under it.
- An endpoint of primary key/secondary index ranges; see the KeyRange type.
Rows that are identified by the Key type are outputs of read operation or targets of delete operation in a mutation. Note that for Insert/Update/InsertOrUpdate/Update mutation types, although they don't require a primary key explicitly, the column list provided must contain enough columns that can comprise a primary key.
Keys are easy to construct. For example, suppose you have a table with a primary key of username and product ID. To make a key for this table:
key := spanner.Key{"john", 16}
See the description of Row and Mutation types for how Go types are mapped to Cloud Spanner types. For convenience, Key type supports a wide range of Go types:
- int, int8, int16, int32, int64, and NullInt64 are mapped to Cloud Spanner's INT64 type.
- uint8, uint16 and uint32 are also mapped to Cloud Spanner's INT64 type.
- float32, float64, NullFloat64 are mapped to Cloud Spanner's FLOAT64 type.
- bool and NullBool are mapped to Cloud Spanner's BOOL type.
- []byte is mapped to Cloud Spanner's BYTES type.
- string and NullString are mapped to Cloud Spanner's STRING type.
- time.Time and NullTime are mapped to Cloud Spanner's TIMESTAMP type.
- civil.Date and NullDate are mapped to Cloud Spanner's DATE type.
- protoreflect.Enum and NullProtoEnum are mapped to Cloud Spanner's ENUM type.
func (Key) AsPrefix
AsPrefix returns a KeyRange for all keys where k is the prefix.
func (Key) String
String implements fmt.Stringer for Key. For string, []byte and NullString, it prints the uninterpreted bytes of their contents, leaving caller with the opportunity to escape the output.
KeyRange
type KeyRange struct {
// Start specifies the left boundary of the key range; End specifies
// the right boundary of the key range.
Start, End Key
// Kind describes whether the boundaries of the key range include
// their keys.
Kind KeyRangeKind
}
A KeyRange represents a range of rows in a table or index.
A range has a Start key and an End key. IncludeStart and IncludeEnd indicate whether the Start and End keys are included in the range.
For example, consider the following table definition:
CREATE TABLE UserEvents (
UserName STRING(MAX),
EventDate STRING(10),
) PRIMARY KEY(UserName, EventDate);
The following keys name rows in this table:
spanner.Key{"Bob", "2014-09-23"}
spanner.Key{"Alfred", "2015-06-12"}
Since the UserEvents table's PRIMARY KEY clause names two columns, each UserEvents key has two elements; the first is the UserName, and the second is the EventDate.
Key ranges with multiple components are interpreted lexicographically by component using the table or index key's declared sort order. For example, the following range returns all events for user "Bob" that occurred in the year 2015:
spanner.KeyRange{
Start: spanner.Key{"Bob", "2015-01-01"},
End: spanner.Key{"Bob", "2015-12-31"},
Kind: ClosedClosed,
}
Start and end keys can omit trailing key components. This affects the inclusion and exclusion of rows that exactly match the provided key components: if IncludeStart is true, then rows that exactly match the provided components of the Start key are included; if IncludeStart is false then rows that exactly match are not included. IncludeEnd and End key behave in the same fashion.
For example, the following range includes all events for "Bob" that occurred during and after the year 2000:
spanner.KeyRange{
Start: spanner.Key{"Bob", "2000-01-01"},
End: spanner.Key{"Bob"},
Kind: ClosedClosed,
}
The next example retrieves all events for "Bob":
spanner.Key{"Bob"}.AsPrefix()
To retrieve events before the year 2000:
spanner.KeyRange{
Start: spanner.Key{"Bob"},
End: spanner.Key{"Bob", "2000-01-01"},
Kind: ClosedOpen,
}
Although we specified a Kind for this KeyRange, we didn't need to, because the default is ClosedOpen. In later examples we'll omit Kind if it is ClosedOpen.
The following range includes all rows in a table or under a index:
spanner.AllKeys()
This range returns all users whose UserName begins with any character from A to C:
spanner.KeyRange{
Start: spanner.Key{"A"},
End: spanner.Key{"D"},
}
This range returns all users whose UserName begins with B:
spanner.KeyRange{
Start: spanner.Key{"B"},
End: spanner.Key{"C"},
}
Key ranges honor column sort order. For example, suppose a table is defined as follows:
CREATE TABLE DescendingSortedTable {
Key INT64,
...
) PRIMARY KEY(Key DESC);
The following range retrieves all rows with key values between 1 and 100 inclusive:
spanner.KeyRange{
Start: spanner.Key{100},
End: spanner.Key{1},
Kind: ClosedClosed,
}
Note that 100 is passed as the start, and 1 is passed as the end, because Key is a descending column in the schema.
func (KeyRange) String
String implements fmt.Stringer for KeyRange type.
KeyRangeKind
type KeyRangeKind int
KeyRangeKind describes the kind of interval represented by a KeyRange: whether it is open or closed on the left and right.
ClosedOpen, ClosedClosed, OpenClosed, OpenOpen
const (
// ClosedOpen is closed on the left and open on the right: the Start
// key is included, the End key is excluded.
ClosedOpen KeyRangeKind = iota
// ClosedClosed is closed on the left and the right: both keys are included.
ClosedClosed
// OpenClosed is open on the left and closed on the right: the Start
// key is excluded, the End key is included.
OpenClosed
// OpenOpen is open on the left and the right: neither key is included.
OpenOpen
)
KeySet
type KeySet interface {
// contains filtered or unexported methods
}
A KeySet defines a collection of Cloud Spanner keys and/or key ranges. All the keys are expected to be in the same table or index. The keys need not be sorted in any particular way.
An individual Key can act as a KeySet, as can a KeyRange. Use the KeySets function to create a KeySet consisting of multiple Keys and KeyRanges. To obtain an empty KeySet, call KeySets with no arguments.
If the same key is specified multiple times in the set (for example if two ranges, two keys, or a key and a range overlap), the Cloud Spanner backend behaves as if the key were only specified once.
func AllKeys
func AllKeys() KeySet
AllKeys returns a KeySet that represents all Keys of a table or a index.
func KeySetFromKeys
KeySetFromKeys returns a KeySet containing the given slice of keys.
func KeySets
KeySets returns the union of the KeySets. If any of the KeySets is AllKeys, then the resulting KeySet will be equivalent to AllKeys.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
// Get some rows from the Accounts table using a secondary index. In this case we get all users who are in Georgia.
iter := client.Single().ReadUsingIndex(context.Background(), "Accounts", "idx_state", spanner.Key{"GA"}, []string{"state"})
// Create a empty KeySet by calling the KeySets function with no parameters.
ks := spanner.KeySets()
// Loop the results of a previous query iterator.
for {
row, err := iter.Next()
if err == iterator.Done {
break
} else if err != nil {
// TODO: Handle error.
}
var id string
err = row.ColumnByName("User", &id)
if err != nil {
// TODO: Handle error.
}
ks = spanner.KeySets(spanner.KeySets(spanner.Key{id}, ks))
}
_ = ks //TODO: Go use the KeySet in another query.
}
LossOfPrecisionHandlingOption
type LossOfPrecisionHandlingOption int
LossOfPrecisionHandlingOption describes the option to deal with loss of precision on numeric values.
NumericRound, NumericError
const (
// NumericRound automatically rounds a numeric value that has a higher
// precision than what is supported by Spanner, e.g., 0.1234567895 rounds
// to 0.123456790.
NumericRound LossOfPrecisionHandlingOption = iota
// NumericError returns an error for numeric values that have a higher
// precision than what is supported by Spanner. E.g. the client returns an
// error if the application tries to insert the value 0.1234567895.
NumericError
)
LossOfPrecisionHandling
var LossOfPrecisionHandling LossOfPrecisionHandlingOption
LossOfPrecisionHandling configures how to deal with loss of precision on numeric values. The value of this configuration is global and will be used for all Spanner clients.
Mutation
type Mutation struct {
// contains filtered or unexported fields
}
A Mutation describes a modification to one or more Cloud Spanner rows. The mutation represents an insert, update, delete, etc on a table.
Many mutations can be applied in a single atomic commit. For purposes of constraint checking (such as foreign key constraints), the operations can be viewed as applying in the same order as the mutations are provided (so that, e.g., a row and its logical "child" can be inserted in the same commit).
The Apply function applies series of mutations. For example,
m := spanner.Insert("User",
[]string{"user_id", "profile"},
[]interface{}{UserID, profile})
_, err := client.Apply(ctx, []*spanner.Mutation{m})
inserts a new row into the User table. The primary key for the new row is UserID (presuming that "user_id" has been declared as the primary key of the "User" table).
To apply a series of mutations as part of an atomic read-modify-write operation, use ReadWriteTransaction.
Updating a row
Changing the values of columns in an existing row is very similar to inserting a new row:
m := spanner.Update("User",
[]string{"user_id", "profile"},
[]interface{}{UserID, profile})
_, err := client.Apply(ctx, []*spanner.Mutation{m})
Deleting a row
To delete a row, use spanner.Delete:
m := spanner.Delete("User", spanner.Key{UserId})
_, err := client.Apply(ctx, []*spanner.Mutation{m})
spanner.Delete accepts a KeySet, so you can also pass in a KeyRange, or use the spanner.KeySets function to build any combination of Keys and KeyRanges.
Note that deleting a row in a table may also delete rows from other tables if cascading deletes are specified in those tables' schemas. Delete does nothing if the named row does not exist (does not yield an error).
Deleting a field
To delete/clear a field within a row, use spanner.Update with the value nil:
m := spanner.Update("User",
[]string{"user_id", "profile"},
[]interface{}{UserID, nil})
_, err := client.Apply(ctx, []*spanner.Mutation{m})
The valid Go types and their corresponding Cloud Spanner types that can be used in the Insert/Update/InsertOrUpdate functions are:
string, *string, NullString - STRING
[]string, []*string, []NullString - STRING ARRAY
[]byte - BYTES
[][]byte - BYTES ARRAY
int, int64, *int64, NullInt64 - INT64
[]int, []int64, []*int64, []NullInt64 - INT64 ARRAY
bool, *bool, NullBool - BOOL
[]bool, []*bool, []NullBool - BOOL ARRAY
float64, *float64, NullFloat64 - FLOAT64
[]float64, []*float64, []NullFloat64 - FLOAT64 ARRAY
time.Time, *time.Time, NullTime - TIMESTAMP
[]time.Time, []*time.Time, []NullTime - TIMESTAMP ARRAY
Date, *Date, NullDate - DATE
[]Date, []*Date, []NullDate - DATE ARRAY
big.Rat, *big.Rat, NullNumeric - NUMERIC
[]big.Rat, []*big.Rat, []NullNumeric - NUMERIC ARRAY
To compare two Mutations for testing purposes, use reflect.DeepEqual.
func Delete
Delete removes the rows described by the KeySet from the table. It succeeds whether or not the keys were present.
Examples
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
m := spanner.Delete("Users", spanner.Key{"alice"})
_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}
keyRange
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
m := spanner.Delete("Users", spanner.KeyRange{
Start: spanner.Key{"alice"},
End: spanner.Key{"bob"},
Kind: spanner.ClosedClosed,
})
_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}
func Insert
Insert returns a Mutation to insert a row into a table. If the row already exists, the write or transaction fails with codes.AlreadyExists.
Example
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
m := spanner.Insert("Users", []string{"name", "email"}, []interface{}{"alice", "a@example.com"})
_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}
func InsertMap
InsertMap returns a Mutation to insert a row into a table, specified by a map of column name to value. If the row already exists, the write or transaction fails with codes.AlreadyExists.
Example
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
m := spanner.InsertMap("Users", map[string]interface{}{
"name": "alice",
"email": "a@example.com",
})
_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}
func InsertOrUpdate
InsertOrUpdate returns a Mutation to insert a row into a table. If the row already exists, it updates it instead. Any column values not explicitly written are preserved.
For a similar example, See Update.
func InsertOrUpdateMap
InsertOrUpdateMap returns a Mutation to insert a row into a table, specified by a map of column to value. If the row already exists, it updates it instead. Any column values not explicitly written are preserved.
For a similar example, See UpdateMap.
func InsertOrUpdateStruct
InsertOrUpdateStruct returns a Mutation to insert a row into a table, specified by a Go struct. If the row already exists, it updates it instead. Any column values not explicitly written are preserved.
The in argument must be a struct or a pointer to a struct. Its exported
fields specify the column names and values. Use a field tag like
spanner:"name"
to provide an alternative column name, or use spanner:"-"
to
ignore the field.
For a similar example, See UpdateStruct.
func InsertStruct
InsertStruct returns a Mutation to insert a row into a table, specified by a Go struct. If the row already exists, the write or transaction fails with codes.AlreadyExists.
The in argument must be a struct or a pointer to a struct. Its exported
fields specify the column names and values. Use a field tag like spanner:"name"
to provide an alternative column name, or use spanner:"-"
to ignore the field.
Example
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
type User struct {
Name, Email string
}
u := User{Name: "alice", Email: "a@example.com"}
m, err := spanner.InsertStruct("Users", u)
if err != nil {
// TODO: Handle error.
}
_ = m // TODO: use with Client.Apply or in a ReadWriteTransaction.
}
func Replace
Replace returns a Mutation to insert a row into a table, deleting any existing row. Unlike InsertOrUpdate, this means any values not explicitly written become NULL.
For a similar example, See Update.
func ReplaceMap
ReplaceMap returns a Mutation to insert a row into a table, deleting any existing row. Unlike InsertOrUpdateMap, this means any values not explicitly written become NULL. The row is specified by a map of column to value.
For a similar example, See UpdateMap.
func ReplaceStruct
ReplaceStruct returns a Mutation to insert a row into a table, deleting any existing row. Unlike InsertOrUpdateMap, this means any values not explicitly written become NULL. The row is specified by a Go struct.
The in argument must be a struct or a pointer to a struct. Its exported
fields specify the column names and values. Use a field tag like spanner:"name"
to provide an alternative column name, or use spanner:"-"
to ignore the field.
For a similar example, See UpdateStruct.
func Update
Update returns a Mutation to update a row in a table. If the row does not already exist, the write or transaction fails.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
if err != nil {
return err
}
var balance int64
if err := row.Column(0, &balance); err != nil {
return err
}
return txn.BufferWrite([]*spanner.Mutation{
spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance + 10}),
})
})
if err != nil {
// TODO: Handle error.
}
}
func UpdateMap
UpdateMap returns a Mutation to update a row in a table, specified by a map of column to value. If the row does not already exist, the write or transaction fails.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
if err != nil {
return err
}
var balance int64
if err := row.Column(0, &balance); err != nil {
return err
}
return txn.BufferWrite([]*spanner.Mutation{
spanner.UpdateMap("Accounts", map[string]interface{}{
"user": "alice",
"balance": balance + 10,
}),
})
})
if err != nil {
// TODO: Handle error.
}
}
func UpdateStruct
UpdateStruct returns a Mutation to update a row in a table, specified by a Go struct. If the row does not already exist, the write or transaction fails.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
type account struct {
User string `spanner:"user"`
Balance int64 `spanner:"balance"`
}
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
row, err := txn.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
if err != nil {
return err
}
var balance int64
if err := row.Column(0, &balance); err != nil {
return err
}
m, err := spanner.UpdateStruct("Accounts", account{
User: "alice",
Balance: balance + 10,
})
if err != nil {
return err
}
return txn.BufferWrite([]*spanner.Mutation{m})
})
if err != nil {
// TODO: Handle error.
}
}
MutationGroup
type MutationGroup struct {
// The Mutations in this group
Mutations []*Mutation
}
A MutationGroup is a list of Mutation to be committed atomically.
NullBool
type NullBool struct {
Bool bool // Bool contains the value when it is non-NULL, and false when NULL.
Valid bool // Valid is true if Bool is not NULL.
}
NullBool represents a Cloud Spanner BOOL that may be NULL.
func (NullBool) GormDataType
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullBool) IsNull
IsNull implements NullableValue.IsNull for NullBool.
func (NullBool) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for NullBool.
func (*NullBool) Scan
Scan implements the sql.Scanner interface.
func (NullBool) String
String implements Stringer.String for NullBool
func (*NullBool) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullBool.
func (NullBool) Value
Value implements the driver.Valuer interface.
NullDate
type NullDate struct {
Date civil.Date // Date contains the value when it is non-NULL, and a zero civil.Date when NULL.
Valid bool // Valid is true if Date is not NULL.
}
NullDate represents a Cloud Spanner DATE that may be null.
func (NullDate) GormDataType
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullDate) IsNull
IsNull implements NullableValue.IsNull for NullDate.
func (NullDate) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for NullDate.
func (*NullDate) Scan
Scan implements the sql.Scanner interface.
func (NullDate) String
String implements Stringer.String for NullDate
func (*NullDate) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullDate.
func (NullDate) Value
Value implements the driver.Valuer interface.
NullFloat32
type NullFloat32 struct {
Float32 float32 // Float32 contains the value when it is non-NULL, and zero when NULL.
Valid bool // Valid is true if FLOAT32 is not NULL.
}
NullFloat32 represents a Cloud Spanner FLOAT32 that may be NULL.
func (NullFloat32) GormDataType
func (n NullFloat32) GormDataType() string
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullFloat32) IsNull
func (n NullFloat32) IsNull() bool
IsNull implements NullableValue.IsNull for NullFloat32.
func (NullFloat32) MarshalJSON
func (n NullFloat32) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.MarshalJSON for NullFloat32.
func (*NullFloat32) Scan
func (n *NullFloat32) Scan(value interface{}) error
Scan implements the sql.Scanner interface.
func (NullFloat32) String
func (n NullFloat32) String() string
String implements Stringer.String for NullFloat32
func (*NullFloat32) UnmarshalJSON
func (n *NullFloat32) UnmarshalJSON(payload []byte) error
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullFloat32.
func (NullFloat32) Value
func (n NullFloat32) Value() (driver.Value, error)
Value implements the driver.Valuer interface.
NullFloat64
type NullFloat64 struct {
Float64 float64 // Float64 contains the value when it is non-NULL, and zero when NULL.
Valid bool // Valid is true if Float64 is not NULL.
}
NullFloat64 represents a Cloud Spanner FLOAT64 that may be NULL.
func (NullFloat64) GormDataType
func (n NullFloat64) GormDataType() string
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullFloat64) IsNull
func (n NullFloat64) IsNull() bool
IsNull implements NullableValue.IsNull for NullFloat64.
func (NullFloat64) MarshalJSON
func (n NullFloat64) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.MarshalJSON for NullFloat64.
func (*NullFloat64) Scan
func (n *NullFloat64) Scan(value interface{}) error
Scan implements the sql.Scanner interface.
func (NullFloat64) String
func (n NullFloat64) String() string
String implements Stringer.String for NullFloat64
func (*NullFloat64) UnmarshalJSON
func (n *NullFloat64) UnmarshalJSON(payload []byte) error
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullFloat64.
func (NullFloat64) Value
func (n NullFloat64) Value() (driver.Value, error)
Value implements the driver.Valuer interface.
NullInt64
type NullInt64 struct {
Int64 int64 // Int64 contains the value when it is non-NULL, and zero when NULL.
Valid bool // Valid is true if Int64 is not NULL.
}
NullInt64 represents a Cloud Spanner INT64 that may be NULL.
func (NullInt64) GormDataType
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullInt64) IsNull
IsNull implements NullableValue.IsNull for NullInt64.
func (NullInt64) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for NullInt64.
func (*NullInt64) Scan
Scan implements the sql.Scanner interface.
func (NullInt64) String
String implements Stringer.String for NullInt64
func (*NullInt64) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullInt64.
func (NullInt64) Value
Value implements the driver.Valuer interface.
NullJSON
type NullJSON struct {
Value interface{} // Val contains the value when it is non-NULL, and nil when NULL.
Valid bool // Valid is true if Json is not NULL.
}
NullJSON represents a Cloud Spanner JSON that may be NULL.
This type must always be used when encoding values to a JSON column in Cloud Spanner.
NullJSON does not implement the driver.Valuer and sql.Scanner interfaces, as the underlying value can be anything. This means that the type NullJSON must also be used when calling sql.Row#Scan(dest ...interface{}) for a JSON column.
func (NullJSON) GormDataType
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullJSON) IsNull
IsNull implements NullableValue.IsNull for NullJSON.
func (NullJSON) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for NullJSON.
func (NullJSON) String
String implements Stringer.String for NullJSON.
func (*NullJSON) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullJSON.
NullNumeric
type NullNumeric struct {
Numeric big.Rat // Numeric contains the value when it is non-NULL, and a zero big.Rat when NULL.
Valid bool // Valid is true if Numeric is not NULL.
}
NullNumeric represents a Cloud Spanner Numeric that may be NULL.
func (NullNumeric) GormDataType
func (n NullNumeric) GormDataType() string
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullNumeric) IsNull
func (n NullNumeric) IsNull() bool
IsNull implements NullableValue.IsNull for NullNumeric.
func (NullNumeric) MarshalJSON
func (n NullNumeric) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.MarshalJSON for NullNumeric.
func (*NullNumeric) Scan
func (n *NullNumeric) Scan(value interface{}) error
Scan implements the sql.Scanner interface.
func (NullNumeric) String
func (n NullNumeric) String() string
String implements Stringer.String for NullNumeric
func (*NullNumeric) UnmarshalJSON
func (n *NullNumeric) UnmarshalJSON(payload []byte) error
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullNumeric.
func (NullNumeric) Value
func (n NullNumeric) Value() (driver.Value, error)
Value implements the driver.Valuer interface.
NullProtoEnum
type NullProtoEnum struct {
ProtoEnumVal protoreflect.Enum // ProtoEnumVal contains the value when Valid is true, and nil when NULL.
Valid bool // Valid is true if ProtoEnumVal is not NULL.
}
NullProtoEnum represents a Cloud Spanner ENUM that may be NULL. To write a NULL value using NullProtoEnum set ProtoEnumVal to typed nil and set Valid to true.
func (NullProtoEnum) IsNull
func (n NullProtoEnum) IsNull() bool
IsNull implements NullableValue.IsNull for NullProtoEnum.
func (NullProtoEnum) MarshalJSON
func (n NullProtoEnum) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.MarshalJSON for NullProtoEnum.
func (NullProtoEnum) String
func (n NullProtoEnum) String() string
String implements Stringer.String for NullProtoEnum.
func (*NullProtoEnum) UnmarshalJSON
func (n *NullProtoEnum) UnmarshalJSON(payload []byte) error
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullProtoEnum.
NullProtoMessage
type NullProtoMessage struct {
ProtoMessageVal proto.Message // ProtoMessageVal contains the value when Valid is true, and nil when NULL.
Valid bool // Valid is true if ProtoMessageVal is not NULL.
}
NullProtoMessage represents a Cloud Spanner PROTO that may be NULL. To write a NULL value using NullProtoMessage set ProtoMessageVal to typed nil and set Valid to true.
func (NullProtoMessage) IsNull
func (n NullProtoMessage) IsNull() bool
IsNull implements NullableValue.IsNull for NullProtoMessage.
func (NullProtoMessage) MarshalJSON
func (n NullProtoMessage) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.MarshalJSON for NullProtoMessage.
func (NullProtoMessage) String
func (n NullProtoMessage) String() string
String implements Stringer.String for NullProtoMessage.
func (*NullProtoMessage) UnmarshalJSON
func (n *NullProtoMessage) UnmarshalJSON(payload []byte) error
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullProtoMessage.
NullRow
type NullRow struct {
Row Row // Row contains the value when it is non-NULL, and a zero Row when NULL.
Valid bool // Valid is true if Row is not NULL.
}
NullRow represents a Cloud Spanner STRUCT that may be NULL. See also the document for Row. Note that NullRow is not a valid Cloud Spanner column Type.
NullString
type NullString struct {
StringVal string // StringVal contains the value when it is non-NULL, and an empty string when NULL.
Valid bool // Valid is true if StringVal is not NULL.
}
NullString represents a Cloud Spanner STRING that may be NULL.
func (NullString) GormDataType
func (n NullString) GormDataType() string
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullString) IsNull
func (n NullString) IsNull() bool
IsNull implements NullableValue.IsNull for NullString.
func (NullString) MarshalJSON
func (n NullString) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.MarshalJSON for NullString.
func (*NullString) Scan
func (n *NullString) Scan(value interface{}) error
Scan implements the sql.Scanner interface.
func (NullString) String
func (n NullString) String() string
String implements Stringer.String for NullString
func (*NullString) UnmarshalJSON
func (n *NullString) UnmarshalJSON(payload []byte) error
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullString.
func (NullString) Value
func (n NullString) Value() (driver.Value, error)
Value implements the driver.Valuer interface.
NullTime
type NullTime struct {
Time time.Time // Time contains the value when it is non-NULL, and a zero time.Time when NULL.
Valid bool // Valid is true if Time is not NULL.
}
NullTime represents a Cloud Spanner TIMESTAMP that may be null.
func (NullTime) GormDataType
GormDataType is used by gorm to determine the default data type for fields with this type.
func (NullTime) IsNull
IsNull implements NullableValue.IsNull for NullTime.
func (NullTime) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for NullTime.
func (*NullTime) Scan
Scan implements the sql.Scanner interface.
func (NullTime) String
String implements Stringer.String for NullTime
func (*NullTime) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for NullTime.
func (NullTime) Value
Value implements the driver.Valuer interface.
NullableValue
type NullableValue interface {
// IsNull returns true if the underlying database value is null.
IsNull() bool
}
NullableValue is the interface implemented by all null value wrapper types.
PGJsonB
type PGJsonB struct {
Value interface{} // Val contains the value when it is non-NULL, and nil when NULL.
Valid bool // Valid is true if PGJsonB is not NULL.
// contains filtered or unexported fields
}
PGJsonB represents a Cloud Spanner PGJsonB that may be NULL.
func (PGJsonB) IsNull
IsNull implements NullableValue.IsNull for PGJsonB.
func (PGJsonB) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for PGJsonB.
func (PGJsonB) String
String implements Stringer.String for PGJsonB.
func (*PGJsonB) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for PGJsonB.
PGNumeric
type PGNumeric struct {
Numeric string // Numeric contains the value when it is non-NULL, and an empty string when NULL.
Valid bool // Valid is true if Numeric is not NULL.
}
PGNumeric represents a Cloud Spanner PG Numeric that may be NULL.
func (PGNumeric) IsNull
IsNull implements NullableValue.IsNull for PGNumeric.
func (PGNumeric) MarshalJSON
MarshalJSON implements json.Marshaler.MarshalJSON for PGNumeric.
func (PGNumeric) String
String implements Stringer.String for PGNumeric
func (*PGNumeric) UnmarshalJSON
UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON for PGNumeric.
Partition
type Partition struct {
// contains filtered or unexported fields
}
Partition defines a segment of data to be read in a batch read or query. A partition can be serialized and processed across several different machines or processes.
func (*Partition) GetPartitionToken
GetPartitionToken returns partition token
func (Partition) MarshalBinary
MarshalBinary implements BinaryMarshaler.
func (*Partition) UnmarshalBinary
UnmarshalBinary implements BinaryUnmarshaler.
PartitionOptions
type PartitionOptions struct {
// The desired data size for each partition generated.
PartitionBytes int64
// The desired maximum number of partitions to return.
MaxPartitions int64
}
PartitionOptions specifies options for a PartitionQueryRequest and PartitionReadRequest. See https://godoc.org/google.golang.org/genproto/googleapis/spanner/v1#PartitionOptions for more details.
QueryOptions
type QueryOptions struct {
Mode *sppb.ExecuteSqlRequest_QueryMode
Options *sppb.ExecuteSqlRequest_QueryOptions
// Priority is the RPC priority to use for the query/update.
Priority sppb.RequestOptions_Priority
// The request tag to use for this request.
RequestTag string
// If this is for a partitioned query and DataBoostEnabled field is set to true, the request will be executed
// via Spanner independent compute resources. Setting this option for regular query operations has no effect.
DataBoostEnabled bool
// QueryOptions option used to set the DirectedReadOptions for all ExecuteSqlRequests which indicate
// which replicas or regions should be used for executing queries.
DirectedReadOptions *sppb.DirectedReadOptions
// Controls whether to exclude recording modifications in current partitioned update operation
// from the allowed tracking change streams(with DDL option allow_txn_exclusion=true). Setting
// this value for any sql/dml requests other than partitioned udpate will receive an error.
ExcludeTxnFromChangeStreams bool
}
QueryOptions provides options for executing a sql query or update statement.
ReadOnlyTransaction
type ReadOnlyTransaction struct {
// contains filtered or unexported fields
}
ReadOnlyTransaction provides a snapshot transaction with guaranteed consistency across reads, but does not allow writes. Read-only transactions can be configured to read at timestamps in the past.
Read-only transactions do not take locks. Instead, they work by choosing a Cloud Spanner timestamp, then executing all reads at that timestamp. Since they do not acquire locks, they do not block concurrent read-write transactions.
Unlike locking read-write transactions, read-only transactions never abort. They can fail if the chosen read timestamp is garbage collected; however, the default garbage collection policy is generous enough that most applications do not need to worry about this in practice. See the documentation of TimestampBound for more details.
A ReadOnlyTransaction consumes resources on the server until Close is called.
func (*ReadOnlyTransaction) AnalyzeQuery
func (t *ReadOnlyTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)
AnalyzeQuery returns the query plan for statement.
func (*ReadOnlyTransaction) Close
func (t *ReadOnlyTransaction) Close()
Close closes a ReadOnlyTransaction, the transaction cannot perform any reads after being closed.
func (*ReadOnlyTransaction) Query
func (t *ReadOnlyTransaction) Query(ctx context.Context, statement Statement) *RowIterator
Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.
Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
_ = iter // TODO: iterate using Next or Do.
}
func (*ReadOnlyTransaction) QueryWithOptions
func (t *ReadOnlyTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator
QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.
func (*ReadOnlyTransaction) QueryWithStats
func (t *ReadOnlyTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator
QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.
func (*ReadOnlyTransaction) Read
func (t *ReadOnlyTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator
Read returns a RowIterator for reading multiple rows from the database.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
iter := client.Single().Read(ctx, "Users",
spanner.KeySets(spanner.Key{"alice"}, spanner.Key{"bob"}),
[]string{"name", "email"})
_ = iter // TODO: iterate using Next or Do.
}
func (*ReadOnlyTransaction) ReadRow
func (t *ReadOnlyTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)
ReadRow reads a single row from the database.
If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Users", spanner.Key{"alice"},
[]string{"name", "email"})
if err != nil {
// TODO: Handle error.
}
_ = row // TODO: use row
}
func (*ReadOnlyTransaction) ReadRowUsingIndex
func (t *ReadOnlyTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)
ReadRowUsingIndex reads a single row from the database using an index.
If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.
func (*ReadOnlyTransaction) ReadRowWithOptions
func (t *ReadOnlyTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)
ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.
If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*ReadOnlyTransaction) ReadUsingIndex
func (t *ReadOnlyTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)
ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
iter := client.Single().ReadUsingIndex(ctx, "Users",
"UsersByEmail",
spanner.KeySets(spanner.Key{"a@example.com"}, spanner.Key{"b@example.com"}),
[]string{"name", "email"})
_ = iter // TODO: iterate using Next or Do.
}
func (*ReadOnlyTransaction) ReadWithOptions
func (t *ReadOnlyTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)
ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.
Example
package main
import (
"context"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
// Use an index, and limit to 100 rows at most.
iter := client.Single().ReadWithOptions(ctx, "Users",
spanner.KeySets(spanner.Key{"a@example.com"}, spanner.Key{"b@example.com"}),
[]string{"name", "email"}, &spanner.ReadOptions{
Index: "UsersByEmail",
Limit: 100,
})
_ = iter // TODO: iterate using Next or Do.
}
func (*ReadOnlyTransaction) Timestamp
func (t *ReadOnlyTransaction) Timestamp() (time.Time, error)
Timestamp returns the timestamp chosen to perform reads and queries in this transaction. The value can only be read after some read or query has either returned some data or completed without returning any data.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
txn := client.Single()
row, err := txn.ReadRow(ctx, "Users", spanner.Key{"alice"},
[]string{"name", "email"})
if err != nil {
// TODO: Handle error.
}
readTimestamp, err := txn.Timestamp()
if err != nil {
// TODO: Handle error.
}
fmt.Println("read happened at", readTimestamp)
_ = row // TODO: use row
}
func (*ReadOnlyTransaction) WithTimestampBound
func (t *ReadOnlyTransaction) WithTimestampBound(tb TimestampBound) *ReadOnlyTransaction
WithTimestampBound specifies the TimestampBound to use for read or query. This can only be used before the first read or query is invoked. Note: bounded staleness is not available with general ReadOnlyTransactions; use a single-use ReadOnlyTransaction instead.
The returned value is the ReadOnlyTransaction so calls can be chained.
Example
package main
import (
"context"
"fmt"
"time"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
txn := client.Single().WithTimestampBound(spanner.MaxStaleness(30 * time.Second))
row, err := txn.ReadRow(ctx, "Users", spanner.Key{"alice"}, []string{"name", "email"})
if err != nil {
// TODO: Handle error.
}
_ = row // TODO: use row
readTimestamp, err := txn.Timestamp()
if err != nil {
// TODO: Handle error.
}
fmt.Println("read happened at", readTimestamp)
}
ReadOptions
type ReadOptions struct {
// The index to use for reading. If non-empty, you can only read columns
// that are part of the index key, part of the primary key, or stored in the
// index due to a STORING clause in the index definition.
Index string
// The maximum number of rows to read. A limit value less than 1 means no
// limit.
Limit int
// Priority is the RPC priority to use for the operation.
Priority sppb.RequestOptions_Priority
// The request tag to use for this request.
RequestTag string
// If this is for a partitioned read and DataBoostEnabled field is set to true, the request will be executed
// via Spanner independent compute resources. Setting this option for regular read operations has no effect.
DataBoostEnabled bool
// ReadOptions option used to set the DirectedReadOptions for all ReadRequests which indicate
// which replicas or regions should be used for running read operations.
DirectedReadOptions *sppb.DirectedReadOptions
// An option to control the order in which rows are returned from a read.
OrderBy sppb.ReadRequest_OrderBy
// A lock hint mechanism to use for this request. This setting is only applicable for
// read-write transaction as as read-only transactions do not take locks.
LockHint sppb.ReadRequest_LockHint
}
ReadOptions provides options for reading rows from a database.
ReadWriteStmtBasedTransaction
type ReadWriteStmtBasedTransaction struct {
// ReadWriteTransaction contains methods for performing transactional reads.
ReadWriteTransaction
// contains filtered or unexported fields
}
ReadWriteStmtBasedTransaction provides a wrapper of ReadWriteTransaction in order to run a read-write transaction in a statement-based way.
This struct is returned by NewReadWriteStmtBasedTransaction and contains Commit() and Rollback() methods to end a transaction.
func NewReadWriteStmtBasedTransaction
func NewReadWriteStmtBasedTransaction(ctx context.Context, c *Client) (*ReadWriteStmtBasedTransaction, error)
NewReadWriteStmtBasedTransaction starts a read-write transaction. Commit() or Rollback() must be called to end a transaction. If Commit() or Rollback() is not called, the session that is used by the transaction will not be returned to the pool and cause a session leak.
This method should only be used when manual error handling and retry management is needed. Cloud Spanner may abort a read/write transaction at any moment, and each statement that is executed on the transaction should be checked for an Aborted error, including queries and read operations.
For most use cases, client.ReadWriteTransaction should be used, as it will handle all Aborted and 'Session not found' errors automatically.
Example
package main
import (
"context"
"errors"
"time"
"cloud.google.com/go/spanner"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
defer client.Close()
f := func(tx *spanner.ReadWriteStmtBasedTransaction) error {
var balance int64
row, err := tx.ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"balance"})
if err != nil {
return err
}
if err := row.Column(0, &balance); err != nil {
return err
}
if balance <= 10 {
return errors.New("insufficient funds in account")
}
balance -= 10
m := spanner.Update("Accounts", []string{"user", "balance"}, []interface{}{"alice", balance})
return tx.BufferWrite([]*spanner.Mutation{m})
}
for {
tx, err := spanner.NewReadWriteStmtBasedTransaction(ctx, client)
if err != nil {
// TODO: Handle error.
break
}
err = f(tx)
if err != nil && status.Code(err) != codes.Aborted {
tx.Rollback(ctx)
// TODO: Handle error.
break
} else if err == nil {
_, err = tx.Commit(ctx)
if err == nil {
break
} else if status.Code(err) != codes.Aborted {
// TODO: Handle error.
break
}
}
// Set a default sleep time if the server delay is absent.
delay := 10 * time.Millisecond
if serverDelay, hasServerDelay := spanner.ExtractRetryDelay(err); hasServerDelay {
delay = serverDelay
}
time.Sleep(delay)
}
}
func NewReadWriteStmtBasedTransactionWithOptions
func NewReadWriteStmtBasedTransactionWithOptions(ctx context.Context, c *Client, options TransactionOptions) (*ReadWriteStmtBasedTransaction, error)
NewReadWriteStmtBasedTransactionWithOptions starts a read-write transaction with configurable options. Commit() or Rollback() must be called to end a transaction. If Commit() or Rollback() is not called, the session that is used by the transaction will not be returned to the pool and cause a session leak.
NewReadWriteStmtBasedTransactionWithOptions is a configurable version of NewReadWriteStmtBasedTransaction.
func (*ReadWriteStmtBasedTransaction) AnalyzeQuery
func (t *ReadWriteStmtBasedTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)
AnalyzeQuery returns the query plan for statement.
func (*ReadWriteStmtBasedTransaction) Commit
Commit tries to commit a readwrite transaction to Cloud Spanner. It also returns the commit timestamp for the transactions.
func (*ReadWriteStmtBasedTransaction) CommitWithReturnResp
func (t *ReadWriteStmtBasedTransaction) CommitWithReturnResp(ctx context.Context) (CommitResponse, error)
CommitWithReturnResp tries to commit a readwrite transaction. It also returns the commit timestamp and stats for the transactions.
func (*ReadWriteStmtBasedTransaction) Query
func (t *ReadWriteStmtBasedTransaction) Query(ctx context.Context, statement Statement) *RowIterator
Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.
Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.
func (*ReadWriteStmtBasedTransaction) QueryWithOptions
func (t *ReadWriteStmtBasedTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator
QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.
func (*ReadWriteStmtBasedTransaction) QueryWithStats
func (t *ReadWriteStmtBasedTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator
QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.
func (*ReadWriteStmtBasedTransaction) Read
func (t *ReadWriteStmtBasedTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator
Read returns a RowIterator for reading multiple rows from the database.
func (*ReadWriteStmtBasedTransaction) ReadRow
func (t *ReadWriteStmtBasedTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)
ReadRow reads a single row from the database.
If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*ReadWriteStmtBasedTransaction) ReadRowUsingIndex
func (t *ReadWriteStmtBasedTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)
ReadRowUsingIndex reads a single row from the database using an index.
If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.
func (*ReadWriteStmtBasedTransaction) ReadRowWithOptions
func (t *ReadWriteStmtBasedTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)
ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.
If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*ReadWriteStmtBasedTransaction) ReadUsingIndex
func (t *ReadWriteStmtBasedTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)
ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.
func (*ReadWriteStmtBasedTransaction) ReadWithOptions
func (t *ReadWriteStmtBasedTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)
ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.
func (*ReadWriteStmtBasedTransaction) Rollback
func (t *ReadWriteStmtBasedTransaction) Rollback(ctx context.Context)
Rollback is called to cancel the ongoing transaction that has not been committed yet.
ReadWriteTransaction
type ReadWriteTransaction struct {
// contains filtered or unexported fields
}
ReadWriteTransaction provides a locking read-write transaction.
This type of transaction is the only way to write data into Cloud Spanner; (Client).Apply, (Client).ApplyAtLeastOnce, (Client).PartitionedUpdate use transactions internally. These transactions rely on pessimistic locking and, if necessary, two-phase commit. Locking read-write transactions may abort, requiring the application to retry. However, the interface exposed by (Client).ReadWriteTransaction eliminates the need for applications to write retry loops explicitly.
Locking transactions may be used to atomically read-modify-write data anywhere in a database. This type of transaction is externally consistent.
Clients should attempt to minimize the amount of time a transaction is active. Faster transactions commit with higher probability and cause less contention. Cloud Spanner attempts to keep read locks active as long as the transaction continues to do reads. Long periods of inactivity at the client may cause Cloud Spanner to release a transaction's locks and abort it.
Reads performed within a transaction acquire locks on the data being read. Writes can only be done at commit time, after all reads have been completed. Conceptually, a read-write transaction consists of zero or more reads or SQL queries followed by a commit.
See (*Client).ReadWriteTransaction for an example.
Semantics
Cloud Spanner can commit the transaction if all read locks it acquired are still valid at commit time, and it is able to acquire write locks for all writes. Cloud Spanner can abort the transaction for any reason. If a commit attempt returns ABORTED, Cloud Spanner guarantees that the transaction has not modified any user data in Cloud Spanner.
Unless the transaction commits, Cloud Spanner makes no guarantees about how long the transaction's locks were held for. It is an error to use Cloud Spanner locks for any sort of mutual exclusion other than between Cloud Spanner transactions themselves.
Aborted transactions
Application code does not need to retry explicitly; RunInTransaction will automatically retry a transaction if an attempt results in an abort. The lock priority of a transaction increases after each prior aborted transaction, meaning that the next attempt has a slightly better chance of success than before.
Under some circumstances (e.g., many transactions attempting to modify the same row(s)), a transaction can abort many times in a short period before successfully committing. Thus, it is not a good idea to cap the number of retries a transaction can attempt; instead, it is better to limit the total amount of wall time spent retrying.
Idle transactions
A transaction is considered idle if it has no outstanding reads or SQL queries and has not started a read or SQL query within the last 10 seconds. Idle transactions can be aborted by Cloud Spanner so that they don't hold on to locks indefinitely. In that case, the commit will fail with error ABORTED.
If this behavior is undesirable, periodically executing a simple SQL query in the transaction (e.g., SELECT 1) prevents the transaction from becoming idle.
func (*ReadWriteTransaction) AnalyzeQuery
func (t *ReadWriteTransaction) AnalyzeQuery(ctx context.Context, statement Statement) (*sppb.QueryPlan, error)
AnalyzeQuery returns the query plan for statement.
func (*ReadWriteTransaction) BatchUpdate
func (t *ReadWriteTransaction) BatchUpdate(ctx context.Context, stmts []Statement) (_ []int64, err error)
BatchUpdate groups one or more DML statements and sends them to Spanner in a single RPC. This is an efficient way to execute multiple DML statements.
A slice of counts is returned, where each count represents the number of affected rows for the given query at the same index. If an error occurs, counts will be returned up to the query that encountered the error.
func (*ReadWriteTransaction) BatchUpdateWithOptions
func (t *ReadWriteTransaction) BatchUpdateWithOptions(ctx context.Context, stmts []Statement, opts QueryOptions) (_ []int64, err error)
BatchUpdateWithOptions groups one or more DML statements and sends them to Spanner in a single RPC. This is an efficient way to execute multiple DML statements.
A slice of counts is returned, where each count represents the number of affected rows for the given query at the same index. If an error occurs, counts will be returned up to the query that encountered the error.
The request tag and priority given in the QueryOptions are included with the RPC. Any other options that are set in the QueryOptions struct are ignored.
func (*ReadWriteTransaction) BufferWrite
func (t *ReadWriteTransaction) BufferWrite(ms []*Mutation) error
BufferWrite adds a list of mutations to the set of updates that will be applied when the transaction is committed. It does not actually apply the write until the transaction is committed, so the operation does not block. The effects of the write won't be visible to any reads (including reads done in the same transaction) until the transaction commits.
See the example for Client.ReadWriteTransaction.
func (*ReadWriteTransaction) Query
func (t *ReadWriteTransaction) Query(ctx context.Context, statement Statement) *RowIterator
Query executes a query against the database. It returns a RowIterator for retrieving the resulting rows.
Query returns only row data, without a query plan or execution statistics. Use QueryWithStats to get rows along with the plan and statistics. Use AnalyzeQuery to get just the plan.
func (*ReadWriteTransaction) QueryWithOptions
func (t *ReadWriteTransaction) QueryWithOptions(ctx context.Context, statement Statement, opts QueryOptions) *RowIterator
QueryWithOptions executes a SQL statment against the database. It returns a RowIterator for retrieving the resulting rows. The sql query execution will be optimized based on the given query options.
func (*ReadWriteTransaction) QueryWithStats
func (t *ReadWriteTransaction) QueryWithStats(ctx context.Context, statement Statement) *RowIterator
QueryWithStats executes a SQL statement against the database. It returns a RowIterator for retrieving the resulting rows. The RowIterator will also be populated with a query plan and execution statistics.
func (*ReadWriteTransaction) Read
func (t *ReadWriteTransaction) Read(ctx context.Context, table string, keys KeySet, columns []string) *RowIterator
Read returns a RowIterator for reading multiple rows from the database.
func (*ReadWriteTransaction) ReadRow
func (t *ReadWriteTransaction) ReadRow(ctx context.Context, table string, key Key, columns []string) (*Row, error)
ReadRow reads a single row from the database.
If no row is present with the given key, then ReadRow returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*ReadWriteTransaction) ReadRowUsingIndex
func (t *ReadWriteTransaction) ReadRowUsingIndex(ctx context.Context, table string, index string, key Key, columns []string) (*Row, error)
ReadRowUsingIndex reads a single row from the database using an index.
If no row is present with the given index, then ReadRowUsingIndex returns an error(spanner.ErrRowNotFound) where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
If more than one row received with the given index, then ReadRowUsingIndex returns an error where spanner.ErrCode(err) is codes.FailedPrecondition.
func (*ReadWriteTransaction) ReadRowWithOptions
func (t *ReadWriteTransaction) ReadRowWithOptions(ctx context.Context, table string, key Key, columns []string, opts *ReadOptions) (*Row, error)
ReadRowWithOptions reads a single row from the database. Pass a ReadOptions to modify the read operation.
If no row is present with the given key, then ReadRowWithOptions returns an error where spanner.ErrCode(err) is codes.NotFound.
To check if the error is spanner.ErrRowNotFound:
if errors.Is(err, spanner.ErrRowNotFound) {
...
}
func (*ReadWriteTransaction) ReadUsingIndex
func (t *ReadWriteTransaction) ReadUsingIndex(ctx context.Context, table, index string, keys KeySet, columns []string) (ri *RowIterator)
ReadUsingIndex calls ReadWithOptions with ReadOptions{Index: index}.
func (*ReadWriteTransaction) ReadWithOptions
func (t *ReadWriteTransaction) ReadWithOptions(ctx context.Context, table string, keys KeySet, columns []string, opts *ReadOptions) (ri *RowIterator)
ReadWithOptions returns a RowIterator for reading multiple rows from the database. Pass a ReadOptions to modify the read operation.
func (*ReadWriteTransaction) Update
func (t *ReadWriteTransaction) Update(ctx context.Context, stmt Statement) (rowCount int64, err error)
Update executes a DML statement against the database. It returns the number of affected rows. Update returns an error if the statement is a query. However, the query is executed, and any data read will be validated upon commit.
func (*ReadWriteTransaction) UpdateWithOptions
func (t *ReadWriteTransaction) UpdateWithOptions(ctx context.Context, stmt Statement, opts QueryOptions) (rowCount int64, err error)
UpdateWithOptions executes a DML statement against the database. It returns the number of affected rows. The given QueryOptions will be used for the execution of this statement.
Row
type Row struct {
// contains filtered or unexported fields
}
A Row is a view of a row of data returned by a Cloud Spanner read. It consists of a number of columns; the number depends on the columns used to construct the read.
The column values can be accessed by index. For instance, if the read specified []string{"photo_id", "caption"}, then each row will contain two columns: "photo_id" with index 0, and "caption" with index 1.
Column values are decoded by using one of the Column, ColumnByName, or Columns methods. The valid values passed to these methods depend on the column type. For example:
var photoID int64
err := row.Column(0, &photoID) // Decode column 0 as an integer.
var caption string
err := row.Column(1, &caption) // Decode column 1 as a string.
// Decode all the columns.
err := row.Columns(&photoID, &caption)
Supported types and their corresponding Cloud Spanner column type(s) are:
*string(not NULL), *NullString - STRING
*[]string, *[]NullString - STRING ARRAY
*[]byte - BYTES
*[][]byte - BYTES ARRAY
*int64(not NULL), *NullInt64 - INT64
*[]int64, *[]NullInt64 - INT64 ARRAY
*bool(not NULL), *NullBool - BOOL
*[]bool, *[]NullBool - BOOL ARRAY
*float32(not NULL), *NullFloat32 - FLOAT32
*[]float32, *[]NullFloat32 - FLOAT32 ARRAY
*float64(not NULL), *NullFloat64 - FLOAT64
*[]float64, *[]NullFloat64 - FLOAT64 ARRAY
*big.Rat(not NULL), *NullNumeric - NUMERIC
*[]big.Rat, *[]NullNumeric - NUMERIC ARRAY
*time.Time(not NULL), *NullTime - TIMESTAMP
*[]time.Time, *[]NullTime - TIMESTAMP ARRAY
*Date(not NULL), *NullDate - DATE
*[]civil.Date, *[]NullDate - DATE ARRAY
*[]*some_go_struct, *[]NullRow - STRUCT ARRAY
*NullJSON - JSON
*[]NullJSON - JSON ARRAY
*GenericColumnValue - any Cloud Spanner type
For TIMESTAMP columns, the returned time.Time object will be in UTC.
To fetch an array of BYTES, pass a [][]byte. To fetch an array of (sub)rows, pass a *[]spanner.NullRow or a *[]some_go_struct where some_go_struct holds all information of the subrow, see spanner.Row.ToStruct for the mapping between a Cloud Spanner row and a Go struct. To fetch an array of other types, pass a *[]spanner.NullXXX type of the appropriate type. Use GenericColumnValue when you don't know in advance what column type to expect.
Row decodes the row contents lazily; as a result, each call to a getter has a chance of returning an error.
A column value may be NULL if the corresponding value is not present in Cloud Spanner. The spanner.NullXXX types (spanner.NullInt64 et al.) allow fetching values that may be null. A NULL BYTES can be fetched into a *[]byte as nil. It is an error to fetch a NULL value into any other type.
func NewRow
NewRow returns a Row containing the supplied data. This can be useful for mocking Cloud Spanner Read and Query responses for unit testing.
func (*Row) Column
Column fetches the value from the ith column, decoding it into ptr. See the Row documentation for the list of acceptable argument types. see Client.ReadWriteTransaction for an example.
func (*Row) ColumnByName
ColumnByName fetches the value from the named column, decoding it into ptr. See the Row documentation for the list of acceptable argument types.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
var balance int64
if err := row.ColumnByName("balance", &balance); err != nil {
// TODO: Handle error.
}
fmt.Println(balance)
}
func (*Row) ColumnIndex
ColumnIndex returns the index of the column with the given name. The comparison is case-sensitive.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
index, err := row.ColumnIndex("balance")
if err != nil {
// TODO: Handle error.
}
fmt.Println(index)
}
func (*Row) ColumnName
ColumnName returns the name of column i, or empty string for invalid column.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
fmt.Println(row.ColumnName(1)) // "balance"
}
func (*Row) ColumnNames
ColumnNames returns all column names of the row.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
fmt.Println(row.ColumnNames())
}
func (*Row) ColumnType
ColumnType returns the Cloud Spanner Type of column i, or nil for invalid column.
func (*Row) ColumnValue
ColumnValue returns the Cloud Spanner Value of column i, or nil for invalid column.
func (*Row) Columns
Columns fetches all the columns in the row at once.
The value of the kth column will be decoded into the kth argument to Columns. See Row for the list of acceptable argument types. The number of arguments must be equal to the number of columns. Pass nil to specify that a column should be ignored.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
var name string
var balance int64
if err := row.Columns(&name, &balance); err != nil {
// TODO: Handle error.
}
fmt.Println(name, balance)
}
func (*Row) Size
Size is the number of columns in the row.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
fmt.Println(row.Size()) // 2
}
func (*Row) String
String implements fmt.stringer.
func (*Row) ToStruct
ToStruct fetches the columns in a row into the fields of a struct. The rules for mapping a row's columns into a struct's exported fields are:
If a field has a
spanner: "column_name"
tag, then decode column 'column_name' into the field. A special case is thespanner: "-"
tag, which instructs ToStruct to ignore the field during decoding.Otherwise, if the name of a field matches the name of a column (ignoring case), decode the column into the field.
The number of columns in the row must match the number of exported fields in the struct. There must be exactly one match for each column in the row. The method will return an error if a column in the row cannot be assigned to a field in the struct.
The fields of the destination struct can be of any type that is acceptable to spanner.Row.Column.
Slice and pointer fields will be set to nil if the source column is NULL, and a non-nil value if the column is not NULL. To decode NULL values of other types, use one of the spanner.NullXXX types as the type of the destination field.
If ToStruct returns an error, the contents of p are undefined. Some fields may have been successfully populated, while others were not; you should not use any of the fields.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"name", "balance"})
if err != nil {
// TODO: Handle error.
}
type Account struct {
Name string
Balance int64
}
var acct Account
if err := row.ToStruct(&acct); err != nil {
// TODO: Handle error.
}
fmt.Println(acct)
}
func (*Row) ToStructLenient
ToStructLenient fetches the columns in a row into the fields of a struct. The rules for mapping a row's columns into a struct's exported fields are:
If a field has a
spanner: "column_name"
tag, then decode column 'column_name' into the field. A special case is thespanner: "-"
tag, which instructs ToStruct to ignore the field during decoding.Otherwise, if the name of a field matches the name of a column (ignoring case), decode the column into the field.
The number of columns in the row and exported fields in the struct do not need to match. Any field in the struct that cannot not be assigned a value from the row is assigned its default value. Any column in the row that does not have a corresponding field in the struct is ignored.
The fields of the destination struct can be of any type that is acceptable to spanner.Row.Column.
Slice and pointer fields will be set to nil if the source column is NULL, and a non-nil value if the column is not NULL. To decode NULL values of other types, use one of the spanner.NullXXX types as the type of the destination field.
If ToStructLenient returns an error, the contents of p are undefined. Some fields may have been successfully populated, while others were not; you should not use any of the fields.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
row, err := client.Single().ReadRow(ctx, "Accounts", spanner.Key{"alice"}, []string{"accountID", "name", "balance"})
if err != nil {
// TODO: Handle error.
}
type Account struct {
Name string
Balance int64
NickName string
}
var acct Account
if err := row.ToStructLenient(&acct); err != nil {
// TODO: Handle error.
}
fmt.Println(acct)
}
RowIterator
type RowIterator struct {
// The plan for the query. Available after RowIterator.Next returns
// iterator.Done if QueryWithStats was called.
QueryPlan *sppb.QueryPlan
// Execution statistics for the query. Available after RowIterator.Next
// returns iterator.Done if QueryWithStats was called.
QueryStats map[string]interface{}
// For a DML statement, the number of rows affected. For PDML, this is a
// lower bound. Available for DML statements after RowIterator.Next returns
// iterator.Done.
RowCount int64
// The metadata of the results of the query. The metadata are available
// after the first call to RowIterator.Next(), unless the first call to
// RowIterator.Next() returned an error that is not equal to iterator.Done.
Metadata *sppb.ResultSetMetadata
// contains filtered or unexported fields
}
RowIterator is an iterator over Rows.
func (*RowIterator) Do
func (r *RowIterator) Do(f func(r *Row) error) error
Do calls the provided function once in sequence for each row in the iteration. If the function returns a non-nil error, Do immediately returns that error.
If there are no rows in the iterator, Do will return nil without calling the provided function.
Do always calls Stop on the iterator.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
err = iter.Do(func(r *spanner.Row) error {
var firstName string
if err := r.Column(0, &firstName); err != nil {
return err
}
fmt.Println(firstName)
return nil
})
if err != nil {
// TODO: Handle error.
}
}
func (*RowIterator) Next
func (r *RowIterator) Next() (*Row, error)
Next returns the next result. Its second return value is iterator.Done if there are no more results. Once Next returns Done, all subsequent calls will return Done.
Example
package main
import (
"context"
"fmt"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
const myDB = "projects/my-project/instances/my-instance/database/my-db"
func main() {
ctx := context.Background()
client, err := spanner.NewClient(ctx, myDB)
if err != nil {
// TODO: Handle error.
}
iter := client.Single().Query(ctx, spanner.NewStatement("SELECT FirstName FROM Singers"))
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
// TODO: Handle error.
}
var firstName string
if err := row.Column(0, &firstName); err != nil {
// TODO: Handle error.
}
fmt.Println(firstName)
}
}
func (*RowIterator) Stop
func (r *RowIterator) Stop()
Stop terminates the iteration. It should be called after you finish using the iterator.
SessionPoolConfig
type SessionPoolConfig struct {
// MaxOpened is the maximum number of opened sessions allowed by the session
// pool. If the client tries to open a session and there are already
// MaxOpened sessions, it will block until one becomes available or the
// context passed to the client method is canceled or times out.
//
// Defaults to NumChannels * 100.
MaxOpened uint64
// MinOpened is the minimum number of opened sessions that the session pool
// tries to maintain. Session pool won't continue to expire sessions if
// number of opened connections drops below MinOpened. However, if a session
// is found to be broken, it will still be evicted from the session pool,
// therefore it is posssible that the number of opened sessions drops below
// MinOpened.
//
// Defaults to 100.
MinOpened uint64
// MaxIdle is the maximum number of idle sessions that are allowed in the
// session pool.
//
// Defaults to 0.
MaxIdle uint64
// MaxBurst is the maximum number of concurrent session creation requests.
//
// Deprecated: MaxBurst exists for historical compatibility and should not
// be used. MaxBurst was used to limit the number of sessions that the
// session pool could create within a time frame. This was an early safety
// valve to prevent a client from overwhelming the backend if a large number
// of sessions was suddenly needed. The session pool would then pause the
// creation of sessions for a while. Such a pause is no longer needed and
// the implementation has been removed from the pool.
//
// Defaults to 10.
MaxBurst uint64
// WriteSessions is the fraction of sessions we try to keep prepared for
// write.
//
// Deprecated: The session pool no longer prepares a fraction of the sessions with a read/write transaction.
// This setting therefore does not have any meaning anymore, and may be removed in the future.
//
// Defaults to 0.2.
WriteSessions float64
// HealthCheckWorkers is number of workers used by health checker for this
// pool.
//
// Defaults to 10.
HealthCheckWorkers int
// HealthCheckInterval is how often the health checker pings a session.
//
// Defaults to 50m.
HealthCheckInterval time.Duration
// MultiplexSessionCheckInterval is the interval at which the multiplexed session is checked whether it needs to be refreshed.
//
// Defaults to 10 mins.
MultiplexSessionCheckInterval time.Duration
// TrackSessionHandles determines whether the session pool will keep track
// of the stacktrace of the goroutines that take sessions from the pool.
// This setting can be used to track down session leak problems.
//
// Defaults to false.
TrackSessionHandles bool
InactiveTransactionRemovalOptions
// contains filtered or unexported fields
}
SessionPoolConfig stores configurations of a session pool.
Statement
A Statement is a SQL query with named parameters.
A parameter placeholder consists of '@' followed by the parameter name. The parameter name is an identifier which must conform to the naming requirements in https://cloud.google.com/spanner/docs/lexical#identifiers. Parameters may appear anywhere that a literal value is expected. The same parameter name may be used more than once. It is an error to execute a statement with unbound parameters. On the other hand, it is allowable to bind parameter names that are not used.
See the documentation of the Row type for how Go types are mapped to Cloud Spanner types.
Examples
arrayOfStructParam
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
stmt := spanner.Statement{
SQL: "SELECT * FROM SINGERS WHERE (FirstName, LastName) IN UNNEST(@singerinfo)",
Params: map[string]interface{}{
"singerinfo": []struct {
FirstName string
LastName string
}{
{"Ringo", "Starr"},
{"John", "Lennon"},
},
},
}
_ = stmt // TODO: Use stmt in Query.
}
regexpContains
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
// Search for accounts with valid emails using regexp as per:
// https://cloud.google.com/spanner/docs/functions-and-operators#regexp_contains
stmt := spanner.Statement{
SQL: `SELECT * FROM users WHERE REGEXP_CONTAINS(email, @valid_email)`,
Params: map[string]interface{}{
"valid_email": `\Q@\E`,
},
}
_ = stmt // TODO: Use stmt in a query.
}
structParam
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
stmt := spanner.Statement{
SQL: "SELECT * FROM SINGERS WHERE (FirstName, LastName) = @singerinfo",
Params: map[string]interface{}{
"singerinfo": struct {
FirstName string
LastName string
}{"Bob", "Dylan"},
},
}
_ = stmt // TODO: Use stmt in Query.
}
func NewStatement
NewStatement returns a Statement with the given SQL and an empty Params map.
Examples
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
stmt := spanner.NewStatement("SELECT FirstName, LastName FROM SINGERS WHERE LastName >= @start")
stmt.Params["start"] = "Dylan"
// TODO: Use stmt in Query.
}
structLiteral
package main
import (
"cloud.google.com/go/spanner"
)
func main() {
stmt := spanner.Statement{
SQL: `SELECT FirstName, LastName FROM SINGERS WHERE LastName = ("Lea", "Martin")`,
}
_ = stmt // TODO: Use stmt in Query.
}
TimestampBound
type TimestampBound struct {
// contains filtered or unexported fields
}
TimestampBound defines how Cloud Spanner will choose a timestamp for a single read/query or read-only transaction.
There are three types of timestamp bound: strong, bounded staleness and exact staleness. Strong is the default.
If the Cloud Spanner database to be read is geographically distributed, stale read-only transactions can execute more quickly than strong or read-write transactions, because they are able to execute far from the leader replica.
Each type of timestamp bound is discussed in detail below. A TimestampBound can be specified when creating transactions, see the documentation of spanner.Client for an example.
Strong reads
Strong reads are guaranteed to see the effects of all transactions that have committed before the start of the read. Furthermore, all rows yielded by a single read are consistent with each other: if any part of the read observes a transaction, all parts of the read see the transaction.
Strong reads are not repeatable: two consecutive strong read-only transactions might return inconsistent results if there are concurrent writes. If consistency across reads is required, the reads should be executed within a transaction or at an exact read timestamp.
Use StrongRead to create a bound of this type.
Exact staleness
An exact staleness timestamp bound executes reads at a user-specified timestamp. Reads at a timestamp are guaranteed to see a consistent prefix of the global transaction history: they observe modifications done by all transactions with a commit timestamp less than or equal to the read timestamp, and observe none of the modifications done by transactions with a larger commit timestamp. They will block until all conflicting transactions that may be assigned commit timestamps less than or equal to the read timestamp have finished.
The timestamp can either be expressed as an absolute Cloud Spanner commit timestamp or a staleness relative to the current time.
These modes do not require a "negotiation phase" to pick a timestamp. As a result, they execute slightly faster than the equivalent boundedly stale concurrency modes. On the other hand, boundedly stale reads usually return fresher results.
Use ReadTimestamp and ExactStaleness to create a bound of this type.
Bounded staleness
Bounded staleness modes allow Cloud Spanner to pick the read timestamp, subject to a user-provided staleness bound. Cloud Spanner chooses the newest timestamp within the staleness bound that allows execution of the reads at the closest available replica without blocking.
All rows yielded are consistent with each other: if any part of the read observes a transaction, all parts of the read see the transaction. Boundedly stale reads are not repeatable: two stale reads, even if they use the same staleness bound, can execute at different timestamps and thus return inconsistent results.
Boundedly stale reads execute in two phases. The first phase negotiates a timestamp among all replicas needed to serve the read. In the second phase, reads are executed at the negotiated timestamp.
As a result of this two-phase execution, bounded staleness reads are usually a little slower than comparable exact staleness reads. However, they are typically able to return fresher results, and are more likely to execute at the closest replica.
Because the timestamp negotiation requires up-front knowledge of which rows will be read, it can only be used with single-use reads and single-use read-only transactions.
Use MinReadTimestamp and MaxStaleness to create a bound of this type.
Old read timestamps and garbage collection
Cloud Spanner continuously garbage collects deleted and overwritten data in the background to reclaim storage space. This process is known as "version GC". By default, version GC reclaims versions after they are one hour old. Because of this, Cloud Spanner cannot perform reads at read timestamps more than one hour in the past. This restriction also applies to in-progress reads and/or SQL queries whose timestamps become too old while executing. Reads and SQL queries with too-old read timestamps fail with the error ErrorCode.FAILED_PRECONDITION.
func ExactStaleness
func ExactStaleness(d time.Duration) TimestampBound
ExactStaleness returns a TimestampBound that will perform reads and queries at an exact staleness.
func MaxStaleness
func MaxStaleness(d time.Duration) TimestampBound
MaxStaleness returns a TimestampBound that will perform reads and queries at a time chosen to be at most "d" stale.
func MinReadTimestamp
func MinReadTimestamp(t time.Time) TimestampBound
MinReadTimestamp returns a TimestampBound that bound that will perform reads and queries at a time chosen to be at least "t".
func ReadTimestamp
func ReadTimestamp(t time.Time) TimestampBound
ReadTimestamp returns a TimestampBound that will peform reads and queries at the given time.
func StrongRead
func StrongRead() TimestampBound
StrongRead returns a TimestampBound that will perform reads and queries at a timestamp where all previously committed transactions are visible.
func (TimestampBound) String
func (tb TimestampBound) String() string
TransactionOptions
type TransactionOptions struct {
CommitOptions CommitOptions
// The transaction tag to use for a read/write transaction.
// This tag is automatically included with each statement and the commit
// request of a read/write transaction.
TransactionTag string
// CommitPriority is the priority to use for the Commit RPC for the
// transaction.
CommitPriority sppb.RequestOptions_Priority
// the transaction lock mode is used to specify a concurrency mode for the
// read/query operations. It works for a read/write transaction only.
ReadLockMode sppb.TransactionOptions_ReadWrite_ReadLockMode
// Controls whether to exclude recording modifications in current transaction
// from the allowed tracking change streams(with DDL option allow_txn_exclusion=true).
ExcludeTxnFromChangeStreams bool
}
TransactionOptions provides options for a transaction.
TransactionOutcomeUnknownError
type TransactionOutcomeUnknownError struct {
// contains filtered or unexported fields
}
TransactionOutcomeUnknownError is wrapped in a Spanner error when the error occurred during a transaction, and the outcome of the transaction is unknown as a result of the error. This could be the case if a timeout or canceled error occurs after a Commit request has been sent, but before the client has received a response from the server.
func (*TransactionOutcomeUnknownError) Error
func (*TransactionOutcomeUnknownError) Error() string
Error implements error.Error.
func (*TransactionOutcomeUnknownError) Unwrap
func (e *TransactionOutcomeUnknownError) Unwrap() error
Unwrap returns the wrapped error (if any).