ReadOptions

The options shared by read requests.

JSON representation 
{

  // Union field consistency_type can be only one of the following:
  "readConsistency": enum (ReadConsistency),
  "transaction": string,
  "newTransaction": {
    object (TransactionOptions)
  },
  "readTime": string
  // End of list of possible types for union field consistency_type.
}
Fields

Union field consistency_type. For Cloud Firestore in Datastore mode, if you don't specify read_consistency then all lookups and queries default to read_consistency=STRONG. Note that, in Cloud Datastore, global queries defaulted to read_consistency=EVENTUAL.

Explicitly setting read_consistency=EVENTUAL will result in eventually consistent lookups and queries. consistency_type can be only one of the following:
readConsistency

enum (ReadConsistency)

The non-transactional read consistency to use.
transaction

string (bytes format)

The identifier of the transaction in which to read. A transaction identifier is returned by a call to Datastore.BeginTransaction.

A base64-encoded string.
newTransaction

object (TransactionOptions)

Options for beginning a new transaction for this request.

The new transaction identifier will be returned in the corresponding response as either LookupResponse.transaction or RunQueryResponse.transaction.
readTime

string (Timestamp format)

Reads entities as they were at the given time. This value is only supported for Cloud Firestore in Datastore mode.

This must be a microsecond precision timestamp within the past one hour, or if Point-in-Time Recovery is enabled, can additionally be a whole minute timestamp within the past 7 days.

A timestamp in RFC3339 UTC "Zulu" format, with nanosecond resolution and up to nine fractional digits. Examples: "2014-10-02T15:01:23Z" and "2014-10-02T15:01:23.045123456Z".

ReadConsistency

The possible values for read consistencies.

Enums
READ_CONSISTENCY_UNSPECIFIED Unspecified. This value must not be used.
STRONG Strong consistency.
EVENTUAL Eventual consistency.