Class Client (2.29.0)

Performs database client operations on Spanner.

Applications use this class to perform operations on Spanner Databases.

Performance

Client objects are relatively cheap to create, copy, and move. However, each Client object must be created with a std::shared_ptr<Connection>, which itself is relatively expensive to create. Therefore, connection instances should be shared when possible. See the MakeConnection() method and the Connection interface for more details.

Thread Safety

Instances of this class created via copy-construction or copy-assignment share the underlying pool of connections. Access to these copies via multiple threads is guaranteed to work. Two threads operating on the same instance of this class is not guaranteed to work.

Error Handling

This class uses StatusOr<T> to report errors. When an operation fails to perform its work the returned StatusOr<T> contains the error details. If the ok() member function in the StatusOr<T> returns true then it contains the expected result. For more information, see the Error Handling Guide.

namespace spanner = ::google::cloud::spanner;

auto db = spanner::Database("my_project", "my_instance", "my_db_id"));
auto conn = spanner::MakeConnection(db);
auto client = spanner::Client(conn);

auto rows = client.Read(...);
using RowType = std::tuple<std::int64_t, std::string>;
for (auto const& row : spanner::StreamOf<RowType>(rows)) {
  // ...
}

Query Options

Most operations that take an SqlStatement may also be modified with query Options. These options can be set at various levels, with more specific levels taking precedence over broader ones. For example, Options that are passed directly to Client::ExecuteQuery() will take precedence over the Client-level defaults (if any), which will themselves take precedence over any environment variables. The following table shows the environment variables that may optionally be set and the query Options setting that they affect.

Environment Variable	Options setting
`SPANNER_OPTIMIZER_VERSION`	`QueryOptimizerVersionOption`
`SPANNER_OPTIMIZER_STATISTICS_PACKAGE`	`QueryOptimizerStatisticsPackageOption`

Constructors

Client(Client const &)

Copy and move support

Parameter
Name	Description
	`Client const &`

Client(Client &&)

Copy and move support

Parameter
Name	Description
	`Client &&`

Client(std::shared_ptr< Connection >, ClientOptions const &)

Backwards compatibility for ClientOptions.

Parameters
Name	Description
`conn`	`std::shared_ptr< Connection >`
`opts`	`ClientOptions const &`

Client(std::shared_ptr< Connection >, std::initializer_list< internal::NonConstructible >)

Backwards compatibility for ClientOptions.

Parameters
Name	Description
`conn`	`std::shared_ptr< Connection >`
	`std::initializer_list< internal::NonConstructible >`

Client(std::shared_ptr< Connection >, Options)

Constructs a Client object using the specified conn and opts.

See MakeConnection() for how to create a connection to Spanner. To help with unit testing, callers may create fake/mock Connection objects that are injected into the Client.

Parameters
Name	Description
`conn`	`std::shared_ptr< Connection >`
`opts`	`Options`

Client()

No default construction.

Operators

operator=(Client const &)

Copy and move support

Parameter
Name	Description
	`Client const &`

Returns
Type	Description
`Client &`

operator=(Client &&)

Copy and move support

Parameter
Name	Description
	`Client &&`

Returns
Type	Description
`Client &`

Functions

Read(std::string, KeySet, std::vector< std::string >, ReadOptions const &)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Read(std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Read(Transaction::SingleUseOptions, std::string, KeySet, std::vector< std::string >, ReadOptions const &)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Read(Transaction::SingleUseOptions, std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Read(Transaction, std::string, KeySet, std::vector< std::string >, ReadOptions const &)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Read(Transaction, std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

PartitionRead(Transaction, std::string, KeySet, std::vector< std::string >, ReadOptions const &, PartitionOptions const &)

Creates a set of partitions that can be used to execute a read operation in parallel.

PartitionRead(Transaction, std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

Creates a set of partitions that can be used to execute a read operation in parallel.

ExecuteQuery(SqlStatement, QueryOptions const &)

Executes a SQL query in a single-use transaction created with the default options.

ExecuteQuery(SqlStatement, std::initializer_list< internal::NonConstructible >)

Executes a SQL query in a single-use transaction created with the default options.

ExecuteQuery(Transaction::SingleUseOptions, SqlStatement, QueryOptions const &)

Executes a SQL query in a single-use transaction created with the transaction_options.

ExecuteQuery(Transaction::SingleUseOptions, SqlStatement, std::initializer_list< internal::NonConstructible >)

Executes a SQL query in a single-use transaction created with the transaction_options.

ExecuteQuery(Transaction, SqlStatement, QueryOptions const &)

Executes a SQL query in an existing transaction.

ExecuteQuery(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

Executes a SQL query in an existing transaction.

ExecuteQuery(QueryPartition const &, QueryOptions const &)

Executes a SQL query on a subset of rows in a database.

ExecuteQuery(QueryPartition const &, std::initializer_list< internal::NonConstructible >)

Executes a SQL query on a subset of rows in a database.

ProfileQuery(SqlStatement, QueryOptions const &)

Profiles a SQL query.

ProfileQuery(SqlStatement, std::initializer_list< internal::NonConstructible >)

Profiles a SQL query.

ProfileQuery(Transaction::SingleUseOptions, SqlStatement, QueryOptions const &)

Profiles a SQL query.

ProfileQuery(Transaction::SingleUseOptions, SqlStatement, std::initializer_list< internal::NonConstructible >)

Profiles a SQL query.

ProfileQuery(Transaction, SqlStatement, QueryOptions const &)

Profiles a SQL query.

ProfileQuery(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

Profiles a SQL query.

ExecuteDml(Transaction, SqlStatement, QueryOptions const &)

Executes a SQL DML statement.

ExecuteDml(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

Executes a SQL DML statement.

ProfileDml(Transaction, SqlStatement, QueryOptions const &)

Executes a SQL query in a single-use transaction created with the default options.

ProfileDml(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

Executes a SQL query in a single-use transaction created with the default options.

AnalyzeSql(Transaction, SqlStatement, QueryOptions const &)

Analyzes the execution plan of a SQL statement.

AnalyzeSql(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

Analyzes the execution plan of a SQL statement.

ExecutePartitionedDml(SqlStatement, QueryOptions const &)

Executes a Partitioned DML SQL query.

ExecutePartitionedDml(SqlStatement, std::initializer_list< internal::NonConstructible >)

Executes a Partitioned DML SQL query.

PartitionQuery(Transaction, SqlStatement, PartitionOptions const &)

Creates a set of partitions that can be used to execute a query operation in parallel.

PartitionQuery(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

Creates a set of partitions that can be used to execute a query operation in parallel.

Commit(std::function< StatusOr< Mutations >(Transaction)> const &, std::unique_ptr< TransactionRerunPolicy >, std::unique_ptr< BackoffPolicy >, CommitOptions const &)

Commits a read-write transaction.

Commit(std::function< StatusOr< Mutations >(Transaction)> const &, std::unique_ptr< TransactionRerunPolicy >, std::unique_ptr< BackoffPolicy >, std::initializer_list< internal::NonConstructible >)

Commits a read-write transaction.

Commit(std::function< StatusOr< Mutations >(Transaction)> const &, CommitOptions const &)

Commits a read-write transaction.

Parameters
Name	Description
`mutator`	`std::function< StatusOr< Mutations >(Transaction)> const &`
`commit_options`	`CommitOptions const &`

Returns
Type	Description
`StatusOr< CommitResult >`

Commit(std::function< StatusOr< Mutations >(Transaction)> const &, std::initializer_list< internal::NonConstructible >)

Backwards compatibility for CommitOptions.

Commit(Mutations, CommitOptions const &)

Commits the mutations, using the options, atomically in order.

Commit(Mutations, std::initializer_list< internal::NonConstructible >)

Commits the mutations, using the options, atomically in order.

Commit(Transaction, Mutations, CommitOptions const &)

Commits a read-write transaction.

Commit(Transaction, Mutations, std::initializer_list< internal::NonConstructible >)

Commits a read-write transaction.

Read(std::string, KeySet, std::vector< std::string >, Options)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Callers can optionally supply a Transaction or Transaction::SingleUseOptions used to create a single-use transaction - or neither, in which case a single-use transaction with default options is used.

Note: No individual row in the ReadResult can exceed 100 MiB, and no column value can exceed 10 MiB.

Example

void ReadData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  auto rows = client.Read("Albums", google::cloud::spanner::KeySet::All(),
                          {"SingerId", "AlbumId", "AlbumTitle"});
  using RowType = std::tuple<std::int64_t, std::int64_t, std::string>;
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "SingerId: " << std::get<0>(*row) << "\t";
    std::cout << "AlbumId: " << std::get<1>(*row) << "\t";
    std::cout << "AlbumTitle: " << std::get<2>(*row) << "\n";
  }

  std::cout << "Read completed for [spanner_read_data]\n";
}

Parameters
Name	Description
`table`	`std::string` The name of the table in the database to be read.
`keys`	`KeySet` Identifies the rows to be yielded. If `read_options.index_name` is set, names keys in that index; otherwise names keys in the primary index of `table`. It is not an error for `keys` to name rows that do not exist in the database; `Read` yields nothing for nonexistent rows.
`columns`	`std::vector< std::string >` The columns of `table` to be returned for each row matching this request.
`opts`	`Options` `Options` used for this request.

Returns
Type	Description
`RowStream`

Read(Transaction::SingleUseOptions, std::string, KeySet, std::vector< std::string >, Options)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Note: No individual row in the ReadResult can exceed 100 MiB, and no column value can exceed 10 MiB.

Example

void ReadData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  auto rows = client.Read("Albums", google::cloud::spanner::KeySet::All(),
                          {"SingerId", "AlbumId", "AlbumTitle"});
  using RowType = std::tuple<std::int64_t, std::int64_t, std::string>;
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "SingerId: " << std::get<0>(*row) << "\t";
    std::cout << "AlbumId: " << std::get<1>(*row) << "\t";
    std::cout << "AlbumTitle: " << std::get<2>(*row) << "\n";
  }

  std::cout << "Read completed for [spanner_read_data]\n";
}

Parameters
Name	Description
`transaction_options`	`Transaction::SingleUseOptions` Execute this read in a single-use transaction with these options.
`table`	`std::string` The name of the table in the database to be read.
`keys`	`KeySet` Identifies the rows to be yielded. If `read_options.index_name` is set, names keys in that index; otherwise names keys in the primary index of `table`. It is not an error for `keys` to name rows that do not exist in the database; `Read` yields nothing for nonexistent rows.
`columns`	`std::vector< std::string >` The columns of `table` to be returned for each row matching this request.
`opts`	`Options` `Options` used for this request.

Returns
Type	Description
`RowStream`

Read(Transaction, std::string, KeySet, std::vector< std::string >, Options)

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteQuery().

Note: No individual row in the ReadResult can exceed 100 MiB, and no column value can exceed 10 MiB.

Example

void ReadData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  auto rows = client.Read("Albums", google::cloud::spanner::KeySet::All(),
                          {"SingerId", "AlbumId", "AlbumTitle"});
  using RowType = std::tuple<std::int64_t, std::int64_t, std::string>;
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "SingerId: " << std::get<0>(*row) << "\t";
    std::cout << "AlbumId: " << std::get<1>(*row) << "\t";
    std::cout << "AlbumTitle: " << std::get<2>(*row) << "\n";
  }

  std::cout << "Read completed for [spanner_read_data]\n";
}

Parameters
Name	Description
`transaction`	`Transaction` Execute this read as part of an existing transaction.
`table`	`std::string` The name of the table in the database to be read.
`keys`	`KeySet` Identifies the rows to be yielded. If `read_options.index_name` is set, names keys in that index; otherwise names keys in the primary index of `table`. It is not an error for `keys` to name rows that do not exist in the database; `Read` yields nothing for nonexistent rows.
`columns`	`std::vector< std::string >` The columns of `table` to be returned for each row matching this request.
`opts`	`Options` `Options` used for this request.

Returns
Type	Description
`RowStream`

Read(ReadPartition const &, Options)

Reads rows from a subset of rows in a database.

Requires a prior call to PartitionRead to obtain the partition information; see the documentation of that method for full details.

Note: No individual row in the ReadResult can exceed 100 MiB, and no column value can exceed 10 MiB.

Example

  google::cloud::StatusOr<spanner::ReadPartition> partition =
      remote_connection.ReceiveReadPartitionFromRemoteMachine();
  if (!partition) throw std::move(partition).status();
  for (auto& row : client.Read(*partition)) {
    if (!row) throw std::move(row).status();
    ProcessRow(*row);
  }

Parameters
Name	Description
`partition`	`ReadPartition const &` A `ReadPartition`, obtained by calling `PartitionRead`.
`opts`	`Options` `Options` used for this request.

Returns
Type	Description
`RowStream`

PartitionRead(Transaction, std::string, KeySet, std::vector< std::string >, Options)

Creates a set of partitions that can be used to execute a read operation in parallel.

Each of the returned partitions can be passed to Read to specify a subset of the read result to read.

There are no ordering guarantees on rows returned among the returned partition, or even within each individual Read call issued with a given partition.

Partitions become invalid when the session used to create them is deleted, is idle for too long, begins a new transaction, or becomes too old. When any of these happen, it is not possible to resume the read, and the whole operation must be restarted from the beginning.

Example

  spanner::Transaction ro_transaction = spanner::MakeReadOnlyTransaction();
  google::cloud::StatusOr<std::vector<spanner::ReadPartition>> partitions =
      client.PartitionRead(
          ro_transaction, "Singers", key_set,
          {"SingerId", "FirstName", "LastName"},
          google::cloud::Options{}.set<spanner::PartitionDataBoostOption>(
              true));
  if (!partitions) throw std::move(partitions).status();
  for (auto& partition : *partitions) {
    remote_connection.SendPartitionToRemoteMachine(partition);
  }

Parameters
Name	Description
`transaction`	`Transaction` The transaction to execute the operation in. Must be a read-only snapshot transaction.
`table`	`std::string` The name of the table in the database to be read.
`keys`	`KeySet` Identifies the rows to be yielded. If `read_options.index_name` is set, names keys in that index; otherwise names keys in the primary index of `table`. It is not an error for `keys` to name rows that do not exist in the database; `Read` yields nothing for nonexistent rows.
`columns`	`std::vector< std::string >` The columns of `table` to be returned for each row matching this request.
`opts`	`Options` `Options` used for this request.

Returns
Type	Description
`StatusOr< std::vector< ReadPartition > >`	A `StatusOr` containing a vector of `ReadPartition` or error status on failure.

ExecuteQuery(SqlStatement, Options)

Executes a SQL query in a single-use transaction created with the default options.

SELECT * ... queries are supported, but there's no guarantee about the order, nor number, of returned columns. Therefore, the caller must look up the wanted values in each row by column name. When the desired column names are known in advance, it is better to list them explicitly in the query's SELECT statement, so that unnecessary values are not returned/ignored, and the column order is known. This enables more efficient and simpler code.

Example

Query with explicitly selected columns.

void QueryData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  spanner::SqlStatement select("SELECT SingerId, LastName FROM Singers");
  using RowType = std::tuple<std::int64_t, std::string>;
  auto rows = client.ExecuteQuery(std::move(select));
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "SingerId: " << std::get<0>(*row) << "\t";
    std::cout << "LastName: " << std::get<1>(*row) << "\n";
  }

  std::cout << "Query completed for [spanner_query_data]\n";
}

Example

Using SELECT *.

void QueryDataSelectStar(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  // With a "SELECT *" query, we don't know the order in which the columns will
  // be returned (nor the number of columns). Therefore, we look up each value
  // based on the column name rather than its position.
  spanner::SqlStatement select_star("SELECT * FROM Singers");
  for (auto& row : client.ExecuteQuery(std::move(select_star))) {
    if (!row) throw std::move(row).status();

    if (auto singer_id = row->get<std::int64_t>("SingerId")) {
      std::cout << "SingerId: " << *singer_id << "\t";
    } else {
      std::cerr << singer_id.status();
    }

    if (auto last_name = row->get<std::string>("LastName")) {
      std::cout << "LastName: " << *last_name;
    } else {
      std::cerr << last_name.status();
    }
    std::cout << "\n";
  }
  std::cout << "Query completed for [spanner_query_data_select_star]\n";
}

Parameters
Name	Description
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`RowStream`

ExecuteQuery(Transaction::SingleUseOptions, SqlStatement, Options)

Executes a SQL query in a single-use transaction created with the transaction_options.

Parameters
Name	Description
`transaction_options`	`Transaction::SingleUseOptions` Execute this query in a single-use transaction with these options.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`RowStream`

ExecuteQuery(Transaction, SqlStatement, Options)

Executes a SQL query in an existing transaction.

Operations inside read-write transactions might return ABORTED. If this occurs, the application should restart the transaction from the beginning.

Can execute a DML statement with a returning clause in a read/write transaction.

Example

Using a DML statement with THEN RETURN.

void UpdateUsingDmlReturning(google::cloud::spanner::Client client) {
  // Update MarketingBudget column for records satisfying a particular
  // condition and return the modified MarketingBudget column of the
  // updated records using `THEN RETURN MarketingBudget`.
  auto commit = client.Commit(
      [&client](google::cloud::spanner::Transaction txn)
          -> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
        auto sql = google::cloud::spanner::SqlStatement(R"""(
            UPDATE Albums SET MarketingBudget = MarketingBudget * 2
              WHERE SingerId = 1 AND AlbumId = 1
              THEN RETURN MarketingBudget
        )""");
        using RowType = std::tuple<absl::optional<std::int64_t>>;
        auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
        // Note: This mutator might be re-run, or its effects discarded, so
        // changing non-transactional state (e.g., by producing output) is,
        // in general, not something to be imitated.
        for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
          if (!row) return std::move(row).status();
          std::cout << "MarketingBudget: ";
          if (std::get<0>(*row).has_value()) {
            std::cout << *std::get<0>(*row);
          } else {
            std::cout << "NULL";
          }
          std::cout << "\n";
        }
        std::cout << "Updated row(s) count: " << rows.RowsModified() << "\n";
        return google::cloud::spanner::Mutations{};
      });
  if (!commit) throw std::move(commit).status();
}

Parameters
Name	Description
`transaction`	`Transaction` Execute this query as part of an existing transaction.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`RowStream`

ExecuteQuery(QueryPartition const &, Options)

Executes a SQL query on a subset of rows in a database.

Requires a prior call to PartitionQuery to obtain the partition information; see the documentation of that method for full details.

Example

  google::cloud::StatusOr<spanner::QueryPartition> partition =
      remote_connection.ReceiveQueryPartitionFromRemoteMachine();
  if (!partition) throw std::move(partition).status();
  for (auto& row : client.ExecuteQuery(*partition)) {
    if (!row) throw std::move(row).status();
    ProcessRow(*row);
  }

Parameters
Name	Description
`partition`	`QueryPartition const &` A `QueryPartition`, obtained by calling `PartitionQuery`.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`RowStream`

ProfileQuery(SqlStatement, Options)

Profiles a SQL query.

Profiling executes the query, provides the resulting rows, ExecutionPlan, and execution statistics.

Operations inside read-write transactions might return kAborted. If this occurs, the application should restart the transaction from the beginning.

Note: Callers must consume all rows from the result before execution statistics and ExecutionPlan are available.

Example

  namespace spanner = ::google::cloud::spanner;
  spanner::SqlStatement select(
      "SELECT AlbumId, AlbumTitle, MarketingBudget"
      " FROM Albums"
      " WHERE AlbumTitle >= 'Aardvark' AND AlbumTitle < 'Goo'");
  auto profile_query_result = client.ProfileQuery(std::move(select));
  for (auto& row : profile_query_result) {
    if (!row) throw std::move(row).status();
    // Discard rows for brevity in this example.
  }

  // Stats are only available after all rows from the result have been read.
  auto execution_stats = profile_query_result.ExecutionStats();
  if (execution_stats) {
    for (auto const& stat : *execution_stats) {
      std::cout << stat.first << ":\t" << stat.second << "\n";
    }
  }

Parameters
Name	Description
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`ProfileQueryResult`

ProfileQuery(Transaction::SingleUseOptions, SqlStatement, Options)

Profiles a SQL query.

Profiling executes the query, provides the resulting rows, ExecutionPlan, and execution statistics.

Operations inside read-write transactions might return kAborted. If this occurs, the application should restart the transaction from the beginning.

Note: Callers must consume all rows from the result before execution statistics and ExecutionPlan are available.

Example

  namespace spanner = ::google::cloud::spanner;
  spanner::SqlStatement select(
      "SELECT AlbumId, AlbumTitle, MarketingBudget"
      " FROM Albums"
      " WHERE AlbumTitle >= 'Aardvark' AND AlbumTitle < 'Goo'");
  auto profile_query_result = client.ProfileQuery(std::move(select));
  for (auto& row : profile_query_result) {
    if (!row) throw std::move(row).status();
    // Discard rows for brevity in this example.
  }

  // Stats are only available after all rows from the result have been read.
  auto execution_stats = profile_query_result.ExecutionStats();
  if (execution_stats) {
    for (auto const& stat : *execution_stats) {
      std::cout << stat.first << ":\t" << stat.second << "\n";
    }
  }

Parameters
Name	Description
`transaction_options`	`Transaction::SingleUseOptions` Execute this query in a single-use transaction with these options.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`ProfileQueryResult`

ProfileQuery(Transaction, SqlStatement, Options)

Profiles a SQL query.

Profiling executes the query, provides the resulting rows, ExecutionPlan, and execution statistics.

Operations inside read-write transactions might return kAborted. If this occurs, the application should restart the transaction from the beginning.

Note: Callers must consume all rows from the result before execution statistics and ExecutionPlan are available.

Example

  namespace spanner = ::google::cloud::spanner;
  spanner::SqlStatement select(
      "SELECT AlbumId, AlbumTitle, MarketingBudget"
      " FROM Albums"
      " WHERE AlbumTitle >= 'Aardvark' AND AlbumTitle < 'Goo'");
  auto profile_query_result = client.ProfileQuery(std::move(select));
  for (auto& row : profile_query_result) {
    if (!row) throw std::move(row).status();
    // Discard rows for brevity in this example.
  }

  // Stats are only available after all rows from the result have been read.
  auto execution_stats = profile_query_result.ExecutionStats();
  if (execution_stats) {
    for (auto const& stat : *execution_stats) {
      std::cout << stat.first << ":\t" << stat.second << "\n";
    }
  }

Parameters
Name	Description
`transaction`	`Transaction` Execute this query as part of an existing transaction.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`ProfileQueryResult`

PartitionQuery(Transaction, SqlStatement, Options)

Creates a set of partitions that can be used to execute a query operation in parallel.

Each of the returned partitions can be passed to ExecuteQuery to specify a subset of the query result to read.

Partitions become invalid when the session used to create them is deleted, is idle for too long, begins a new transaction, or becomes too old. When any of these happen, it is not possible to resume the query, and the whole operation must be restarted from the beginning.

Example

  google::cloud::StatusOr<std::vector<spanner::QueryPartition>> partitions =
      client.PartitionQuery(
          spanner::MakeReadOnlyTransaction(),
          spanner::SqlStatement(
              "SELECT SingerId, FirstName, LastName FROM Singers"),
          google::cloud::Options{}.set<spanner::PartitionDataBoostOption>(
              true));
  if (!partitions) throw std::move(partitions).status();
  for (auto& partition : *partitions) {
    remote_connection.SendPartitionToRemoteMachine(partition);
  }

Parameters
Name	Description
`transaction`	`Transaction` The transaction to execute the operation in. Must be a read-only snapshot transaction.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` `Options` used for this request.

Returns
Type	Description
`StatusOr< std::vector< QueryPartition > >`	A `StatusOr` containing a vector of `QueryPartition`s or error status on failure.

ExecuteDml(Transaction, SqlStatement, Options)

Executes a SQL DML statement.

Operations inside read-write transactions might return ABORTED. If this occurs, the application should restart the transaction from the beginning.

Example

  using ::google::cloud::StatusOr;
  namespace spanner = ::google::cloud::spanner;
  std::int64_t rows_inserted;
  auto commit_result = client.Commit(
      [&client, &rows_inserted](
          spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
        auto insert = client.ExecuteDml(
            std::move(txn),
            spanner::SqlStatement(
                "INSERT INTO Singers (SingerId, FirstName, LastName)"
                "  VALUES (10, 'Virginia', 'Watson')"));
        if (!insert) return std::move(insert).status();
        rows_inserted = insert->RowsModified();
        return spanner::Mutations{};
      });
  if (!commit_result) throw std::move(commit_result).status();
  std::cout << "Rows inserted: " << rows_inserted;

Parameters
Name	Description
`transaction`	`Transaction` Execute this query as part of an existing transaction.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`StatusOr< DmlResult >`

ProfileDml(Transaction, SqlStatement, Options)

Profiles a SQL DML statement.

Profiling executes the DML statement, provides the modified row count, ExecutionPlan, and execution statistics.

Operations inside read-write transactions might return ABORTED. If this occurs, the application should restart the transaction from the beginning.

Example

  spanner::ProfileDmlResult dml_result;
  auto commit_result = client.Commit(
      [&client,
       &dml_result](spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
        auto update = client.ProfileDml(
            std::move(txn),
            spanner::SqlStatement(
                "UPDATE Albums SET MarketingBudget = MarketingBudget * 2"
                "  WHERE SingerId = 1 AND AlbumId = 1"));
        if (!update) return std::move(update).status();
        dml_result = *std::move(update);
        return spanner::Mutations{};
      });
  if (!commit_result) throw std::move(commit_result).status();

  // Stats only available after statement has been executed.
  std::cout << "Rows modified: " << dml_result.RowsModified();
  auto execution_stats = dml_result.ExecutionStats();
  if (execution_stats) {
    for (auto const& stat : *execution_stats) {
      std::cout << stat.first << ":\t" << stat.second << "\n";
    }
  }

Parameters
Name	Description
`transaction`	`Transaction` Execute this query as part of an existing transaction.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`StatusOr< ProfileDmlResult >`

AnalyzeSql(Transaction, SqlStatement, Options)

Analyzes the execution plan of a SQL statement.

Analyzing provides the ExecutionPlan, but does not execute the SQL statement.

Operations inside read-write transactions might return ABORTED. If this occurs, the application should restart the transaction from the beginning.

Example

  // For a SQL query to be partitionable, it has to satisfy some conditions.
  // For example, if it has a Distributed Union operator, the Distributed
  // Union operator must be the first operator in the `ExecutionPlan`.
  // For detailed definition, please refer to
  // https://cloud.google.com/spanner/docs/reads#read_data_in_parallel
  auto is_partitionable = [](spanner::ExecutionPlan const& plan) {
    return (!plan.plan_nodes().empty() &&
            plan.plan_nodes(0).kind() ==
                google::spanner::v1::PlanNode::RELATIONAL &&
            plan.plan_nodes(0).display_name() == "Distributed Union");
  };

  google::cloud::StatusOr<spanner::ExecutionPlan> plan = client.AnalyzeSql(
      spanner::MakeReadOnlyTransaction(),
      spanner::SqlStatement(
          "SELECT SingerId, FirstName, LastName FROM Singers"));
  if (!plan) throw std::move(plan).status();
  if (!is_partitionable(*plan)) {
    throw std::runtime_error("Query is not partitionable");
  }

Parameters
Name	Description
`transaction`	`Transaction` Execute this query as part of an existing transaction.
`statement`	`SqlStatement` The SQL statement to execute.
`opts`	`Options` (optional) The `Options` to use for this call. If given, these will take precedence over the options set at the client and environment levels.

Returns
Type	Description
`StatusOr< ExecutionPlan >`

ExecuteBatchDml(Transaction, std::vector< SqlStatement >, Options)

Executes a batch of SQL DML statements.

This method allows many statements to be run with lower latency than submitting them sequentially with ExecuteDml.

Statements are executed in order, sequentially. Execution will stop at the first failed statement; the remaining statements will not run.

As with all read-write transactions, the results will not be visible outside of the transaction until it is committed. For that reason, it is advisable to run this method from a Commit mutator.

Example

void DmlStructs(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  std::int64_t rows_modified = 0;
  auto commit_result =
      client.Commit([&client, &rows_modified](spanner::Transaction const& txn)
                        -> google::cloud::StatusOr<spanner::Mutations> {
        auto singer_info = std::make_tuple("Marc", "Richards");
        auto sql = spanner::SqlStatement(
            "UPDATE Singers SET FirstName = 'Keith' WHERE "
            "STRUCT<FirstName String, LastName String>(FirstName, LastName) "
            "= @name",
            {{"name", spanner::Value(std::move(singer_info))}});
        auto dml_result = client.ExecuteDml(txn, std::move(sql));
        if (!dml_result) return std::move(dml_result).status();
        rows_modified = dml_result->RowsModified();
        return spanner::Mutations{};
      });
  if (!commit_result) throw std::move(commit_result).status();
  std::cout << rows_modified
            << " update was successful [spanner_dml_structs]\n";
}

Parameters
Name	Description
`transaction`	`Transaction` The read-write transaction to execute the operation in.
`statements`	`std::vector< SqlStatement >` The list of statements to execute in this batch. Statements are executed serially, such that the effects of statement i are visible to statement i+1. Each statement must be a DML statement. Execution will stop at the first failed statement; the remaining statements will not run. Must not be empty.
`opts`	`Options` (optional) The options to use for this call. Expected options are any of the types in the following option lists. `google::cloud::RequestOptionList`

Returns
Type	Description
`StatusOr< BatchDmlResult >`

Commit(std::function< StatusOr< Mutations >(Transaction)> const &, std::unique_ptr< TransactionRerunPolicy >, std::unique_ptr< BackoffPolicy >, Options)

Commits a read-write transaction.

Calls the mutator in the context of a new read-write transaction. The mutator can execute read/write operations using the transaction, and returns any additional Mutations to commit.

If the mutator succeeds and the transaction commits, then Commit() returns the CommitResult.

If the mutator returns a non-rerunnable status (according to the rerun_policy), the transaction is rolled back and that status is returned. Similarly, if the transaction fails to commit with a non- rerunnable status, that status is returned.

Otherwise the whole process repeats (subject to rerun_policy and backoff_policy), by building a new transaction and re-running the mutator. The lock priority of the operation increases after each rerun, meaning that the next attempt has a slightly better chance of success.

Note that the mutator should only return a rerunnable status when the transaction is no longer usable (e.g., it was aborted). Otherwise the transaction will be leaked.

Example

void CommitWithPolicies(google::cloud::spanner::Client client) {
  using ::google::cloud::StatusOr;
  namespace spanner = ::google::cloud::spanner;
  auto commit = client.Commit(
      [&client](spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
        auto update = client.ExecuteDml(
            std::move(txn),
            spanner::SqlStatement(
                "UPDATE Albums SET MarketingBudget = MarketingBudget * 2"
                "  WHERE SingerId = 1 AND AlbumId = 1"));
        if (!update) return std::move(update).status();
        return spanner::Mutations{};
      },
      // Retry for up to 42 minutes.
      spanner::LimitedTimeTransactionRerunPolicy(std::chrono::minutes(42))
          .clone(),
      // After a failure backoff for 2 seconds (with jitter), then triple the
      // backoff time on each retry, up to 5 minutes.
      spanner::ExponentialBackoffPolicy(std::chrono::seconds(2),
                                        std::chrono::minutes(5), 3.0)
          .clone());
  if (!commit) throw std::move(commit).status();
  std::cout << "commit-with-policies was successful\n";
}

Parameters
Name	Description
`mutator`	`std::function< StatusOr< Mutations >(Transaction)> const &` the function called to create mutations
`rerun_policy`	`std::unique_ptr< TransactionRerunPolicy >` controls for how long (or how many times) the mutator will be rerun after the transaction aborts.
`backoff_policy`	`std::unique_ptr< BackoffPolicy >` controls how long `Commit` waits between reruns.
`opts`	`Options` (optional) The options to use for this call. Expected options include any of the following types: `google::cloud::spanner::CommitReturnStatsOption` `google::cloud::spanner::RequestPriorityOption` `google::cloud::spanner::TransactionTagOption`

Exceptions
Type	Description
`Rethrows`	any exception thrown by ``mutator`` (after rolling back the transaction). However, a [`RuntimeStatusError`](xref:classgoogle_1_1cloud_1_1RuntimeStatusError) exception is instead consumed and converted into a `mutator` return value of the enclosed [`Status`](xref:classgoogle_1_1cloud_1_1Status).

Returns
Type	Description
`StatusOr< CommitResult >`

Commit(std::function< StatusOr< Mutations >(Transaction)> const &, Options)

Commits a read-write transaction.

Same as above, but uses the default rerun and backoff policies.

Example

  using ::google::cloud::StatusOr;
  namespace spanner = ::google::cloud::spanner;
  auto commit_result = client.Commit(
      [&client](spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
        auto update = client.ExecuteDml(
            std::move(txn),
            spanner::SqlStatement(
                "UPDATE Albums SET MarketingBudget = MarketingBudget * 2"
                "  WHERE SingerId = 1 AND AlbumId = 1"));
        if (!update) return std::move(update).status();
        return spanner::Mutations{};
      });
  if (!commit_result) throw std::move(commit_result).status();

Parameters
Name	Description
`mutator`	`std::function< StatusOr< Mutations >(Transaction)> const &` the function called to create mutations
`opts`	`Options` (optional) The options to use for this call.

Returns
Type	Description
`StatusOr< CommitResult >`

Commit(Mutations, Options)

Commits the mutations, using the options, atomically in order.

Example

  namespace spanner = ::google::cloud::spanner;
  auto commit_result = client.Commit(spanner::Mutations{
      spanner::UpdateMutationBuilder("Albums",
                                     {"SingerId", "AlbumId", "MarketingBudget"})
          .EmplaceRow(1, 1, 100000)
          .EmplaceRow(2, 2, 500000)
          .Build()});
  if (!commit_result) throw std::move(commit_result).status();

This function uses the re-run loop described above with the default policies.

Parameters
Name	Description
`mutations`	`Mutations`
`opts`	`Options`

Returns
Type	Description
`StatusOr< CommitResult >`

Commit(Transaction, Mutations, Options)

Commits a read-write transaction.

The commit might return a kAborted error. This can occur at any time. Commonly the cause is conflicts with concurrent transactions, however it can also happen for a variety of other reasons. If Commit returns kAborted, the caller may try to reapply the mutations within a new read-write transaction (which should share lock priority with the aborted transaction so that the new attempt has a slightly better chance of success).

Warning: It is an error to call Commit with a read-only transaction.

Note: Prefer the previous Commit overloads if you want to simply reapply mutations after a kAborted error.

Parameters
Name	Description
`transaction`	`Transaction` The transaction to commit.
`mutations`	`Mutations` The mutations to be executed when this transaction commits. All mutations are applied atomically, in the order they appear in this list.
`opts`	`Options` (optional) The options to use for this call.

Returns
Type	Description
`StatusOr< CommitResult >`	A `StatusOr` containing the result of the commit or error status on failure.

CommitAtLeastOnce(Transaction::ReadWriteOptions, Mutations, Options)

Commits a write transaction with at-least-once semantics.

Apply the given mutations atomically, using a single RPC, and therefore without replay protection. That is, it is possible that the mutations will be applied more than once. If the mutations are not idempotent, this may lead to a failure (for example, an insert may fail with "already exists" even though the row did not exist before the call was made). Accordingly, this call may only be appropriate for idempotent, latency- sensitive and/or high-throughput blind writing.

Note: Prefer the Commit overloads if you want exactly-once semantics or want to reapply mutations after a kAborted error.

Example

  namespace spanner = ::google::cloud::spanner;

  // Delete the album with key (2,2) without automatic re-run (e.g., if the
  // transaction was aborted) or replay protection, but using a single RPC.
  auto commit_result = client.CommitAtLeastOnce(
      spanner::Transaction::ReadWriteOptions(),
      spanner::Mutations{
          spanner::DeleteMutationBuilder(
              "Albums", spanner::KeySet().AddKey(spanner::MakeKey(2, 2)))
              .Build()});

  if (commit_result) {
    std::cout << "Delete was successful\n";
  } else if (commit_result.status().code() ==
             google::cloud::StatusCode::kNotFound) {
    std::cout << "Delete was successful but seemingly replayed\n";
  } else if (commit_result.status().code() ==
             google::cloud::StatusCode::kAborted) {
    std::cout << "Delete was aborted\n";
  } else {
    throw std::move(commit_result).status();
  }

Parameters
Name	Description
`transaction_options`	`Transaction::ReadWriteOptions` Execute the commit in a temporary transaction with these options.
`mutations`	`Mutations` The mutations to be executed when this transaction commits. All mutations are applied atomically, in the order they appear in this list.
`opts`	`Options` (optional) The options to use for this call.

Returns
Type	Description
`StatusOr< CommitResult >`	A `StatusOr` containing the result of the commit or error status on failure.

CommitAtLeastOnce(std::vector< Mutations >, Options)

Commits the mutation groups, batched efficiently into transactions with at-least-once semantics, using a single RPC.

All mutations within a group are committed atomically. There is no atomicity or ordering between groups however, so all groups must be independent of each other.

Partial failure is possible. That is, some groups can commit successfully while others fail. The results of individual batches are returned via the response stream as their transactions complete.

Mutation groups are not replay protected. That is, it is possible that each mutation group may be applied more than once. If the mutations are not idempotent, this may lead to a failure. For example, replays of an insert mutation might produce an "already exists" error, or, if you use generated or commit-timestamp-based keys, might result in additional rows being added to the mutation's table. We recommend structuring your mutation groups to be idempotent to avoid this issue.

Note: Prefer the Commit overloads if you want exactly-once semantics or want to automatically reapply mutations after a kAborted error.

Example

  namespace spanner = ::google::cloud::spanner;
  // Use upserts as mutation groups are not replay protected.
  auto commit_results = client.CommitAtLeastOnce({
      // group #0
      spanner::Mutations{
          spanner::InsertOrUpdateMutationBuilder(
              "Singers", {"SingerId", "FirstName", "LastName"})
              .EmplaceRow(16, "Scarlet", "Terry")
              .Build(),
      },
      // group #1
      spanner::Mutations{
          spanner::InsertOrUpdateMutationBuilder(
              "Singers", {"SingerId", "FirstName", "LastName"})
              .EmplaceRow(17, "Marc", "")
              .EmplaceRow(18, "Catalina", "Smith")
              .Build(),
          spanner::InsertOrUpdateMutationBuilder(
              "Albums", {"SingerId", "AlbumId", "AlbumTitle"})
              .EmplaceRow(17, 1, "Total Junk")
              .EmplaceRow(18, 2, "Go, Go, Go")
              .Build(),
      },
  });
  for (auto& commit_result : commit_results) {
    if (!commit_result) throw std::move(commit_result).status();
    std::cout << "Mutation group indexes [";
    for (auto index : commit_result->indexes) std::cout << " " << index;
    std::cout << " ]: ";
    if (commit_result->commit_timestamp) {
      auto const& ts = *commit_result->commit_timestamp;
      std::cout << "Committed at " << ts.get<absl::Time>().value();
    } else {
      std::cout << commit_result->commit_timestamp.status();
    }
    std::cout << "\n";
  }

Parameters

Name Description

mutation_groups

std::vector< Mutations >

The mutation groups to be batched into temporary transactions and committed.

opts

Options

(optional) The options to use for this call. Expected options include any of the following types:

Returns
Type	Description
`BatchedCommitResultStream`

Rollback(Transaction, Options)

Rolls back a read-write transaction, releasing any locks it holds.

At any time before Commit, the client can call Rollback to abort the transaction. It is a good idea to call this for any read-write transaction that includes one or more Read, ExecuteQuery, or ExecuteDml requests and ultimately decides not to commit.

Warning: It is an error to call Rollback with a read-only transaction.

Parameters
Name	Description
`transaction`	`Transaction` The transaction to roll back.
`opts`	`Options` (optional) The options to use for this call.

Returns
Type	Description
`Status`	The error status of the rollback.

ExecutePartitionedDml(SqlStatement, Options)

Executes a Partitioned DML SQL query.

Example

void DmlPartitionedDelete(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  auto result = client.ExecutePartitionedDml(
      spanner::SqlStatement("DELETE FROM Singers WHERE SingerId > 10"));
  if (!result) throw std::move(result).status();
  std::cout << "Deleted at least " << result->row_count_lower_bound
            << " row(s) [spanner_dml_partitioned_delete]\n";
}

Class Client (2.29.0)

Performance

Thread Safety

Error Handling

Query Options

See Also

See Also

Constructors

Client(Client const &)

Client(Client &&)

Client(std::shared_ptr< Connection >, ClientOptions const &)

Client(std::shared_ptr< Connection >, std::initializer_list< internal::NonConstructible >)

Client(std::shared_ptr< Connection >, Options)

Client()

Operators

operator=(Client const &)

operator=(Client &&)

Functions

Read(std::string, KeySet, std::vector< std::string >, ReadOptions const &)

See Also

Read(std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

See Also

Read(Transaction::SingleUseOptions, std::string, KeySet, std::vector< std::string >, ReadOptions const &)

See Also

Read(Transaction::SingleUseOptions, std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

See Also

Read(Transaction, std::string, KeySet, std::vector< std::string >, ReadOptions const &)

See Also

Read(Transaction, std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

See Also

PartitionRead(Transaction, std::string, KeySet, std::vector< std::string >, ReadOptions const &, PartitionOptions const &)

See Also

PartitionRead(Transaction, std::string, KeySet, std::vector< std::string >, std::initializer_list< internal::NonConstructible >)

See Also

ExecuteQuery(SqlStatement, QueryOptions const &)

See Also

ExecuteQuery(SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ExecuteQuery(Transaction::SingleUseOptions, SqlStatement, QueryOptions const &)

See Also

ExecuteQuery(Transaction::SingleUseOptions, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ExecuteQuery(Transaction, SqlStatement, QueryOptions const &)

See Also

ExecuteQuery(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ExecuteQuery(QueryPartition const &, QueryOptions const &)

See Also

ExecuteQuery(QueryPartition const &, std::initializer_list< internal::NonConstructible >)

See Also

ProfileQuery(SqlStatement, QueryOptions const &)

See Also

ProfileQuery(SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ProfileQuery(Transaction::SingleUseOptions, SqlStatement, QueryOptions const &)

See Also

ProfileQuery(Transaction::SingleUseOptions, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ProfileQuery(Transaction, SqlStatement, QueryOptions const &)

See Also

ProfileQuery(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ExecuteDml(Transaction, SqlStatement, QueryOptions const &)

See Also

ExecuteDml(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ProfileDml(Transaction, SqlStatement, QueryOptions const &)

See Also

ProfileDml(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

AnalyzeSql(Transaction, SqlStatement, QueryOptions const &)

See Also

AnalyzeSql(Transaction, SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

ExecutePartitionedDml(SqlStatement, QueryOptions const &)

See Also

ExecutePartitionedDml(SqlStatement, std::initializer_list< internal::NonConstructible >)

See Also

PartitionQuery(Transaction, SqlStatement, PartitionOptions const &)

See Also