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    TransactionOptions

    Options to use for transactions.

    JSON representation 
     { 
 "excludeTxnFromChangeStreams" 
 : 
 boolean 
 , 
 "isolationLevel" 
 : 
 enum (  IsolationLevel 
 
) 
 , 
 // Union field mode 
can be only one of the following: 
 "readWrite" 
 : 
 { 
 object (  ReadWrite 
 
) 
 } 
 , 
 "partitionedDml" 
 : 
 { 
 object (  PartitionedDml 
 
) 
 } 
 , 
 "readOnly" 
 : 
 { 
 object (  ReadOnly 
 
) 
 } 
 // End of list of possible types for union field mode 
. 
 }
    Fields
    excludeTxnFromChangeStreams

    boolean

    When excludeTxnFromChangeStreams is set to true , it prevents read or write transactions from being tracked in change streams.

    • If the DDL option allow_txn_exclusion is set to true , then the updates made within this transaction aren't recorded in the change stream.

    • If you don't set the DDL option allow_txn_exclusion or if it's set to false , then the updates made within this transaction are recorded in the change stream.

    When excludeTxnFromChangeStreams is set to false or not set, modifications from this transaction are recorded in all change streams that are tracking columns modified by these transactions.

    The excludeTxnFromChangeStreams option can only be specified for read-write or partitioned DML transactions, otherwise the API returns an INVALID_ARGUMENT error.

    isolationLevel

    enum ( IsolationLevel )

    Isolation level for the transaction.

    Union field mode . Required. The type of transaction. mode can be only one of the following:
    readWrite

    object ( ReadWrite )

    Transaction may write.

    Authorization to begin a read-write transaction requires spanner.databases.beginOrRollbackReadWriteTransaction permission on the session resource.

    partitionedDml

    object ( PartitionedDml )

    Partitioned DML transaction.

    Authorization to begin a Partitioned DML transaction requires spanner.databases.beginPartitionedDmlTransaction permission on the session resource.

    readOnly

    object ( ReadOnly )

    Transaction does not write.

    Authorization to begin a read-only transaction requires spanner.databases.beginReadOnlyTransaction permission on the session resource.

    ReadWrite

    Message type to initiate a read-write transaction. Currently this transaction type has no options.

    JSON representation 
     { 
 "multiplexedSessionPreviousTransactionId" 
 : 
 string 
 }
    Fields
    multiplexedSessionPreviousTransactionId

    string ( bytes format)

    Optional. Clients should pass the transaction ID of the previous transaction attempt that was aborted if this transaction is being executed on a multiplexed session.

    A base64-encoded string.

    PartitionedDml

    This type has no fields.

    Message type to initiate a Partitioned DML transaction.

    ReadOnly

    Message type to initiate a read-only transaction.

    JSON representation 
     { 
 "returnReadTimestamp" 
 : 
 boolean 
 , 
 // Union field timestamp_bound 
can be only one of the following: 
 "strong" 
 : 
 boolean 
 , 
 "minReadTimestamp" 
 : 
 string 
 , 
 "maxStaleness" 
 : 
 string 
 , 
 "readTimestamp" 
 : 
 string 
 , 
 "exactStaleness" 
 : 
 string 
 // End of list of possible types for union field timestamp_bound 
. 
 }
    Fields
    returnReadTimestamp

    boolean

    If true, the Cloud Spanner-selected read timestamp is included in the Transaction message that describes the transaction.

    Union field timestamp_bound . How to choose the timestamp for the read-only transaction. timestamp_bound can be only one of the following:
    strong

    boolean

    sessions.read at a timestamp where all previously committed transactions are visible.

    minReadTimestamp

    string ( Timestamp format)

    Executes all reads at a timestamp >= minReadTimestamp .

    This is useful for requesting fresher data than some previous read, or data that is fresh enough to observe the effects of some previously committed transaction whose timestamp is known.

    Note that this option can only be used in single-use transactions.

    A timestamp in RFC3339 UTC "Zulu" format, accurate to nanoseconds. Example: "2014-10-02T15:01:23.045123456Z" .

    Uses RFC 3339, where generated output will always be Z-normalized and uses 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted. Examples: "2014-10-02T15:01:23Z" , "2014-10-02T15:01:23.045123456Z" or "2014-10-02T15:01:23+05:30" .

    maxStaleness

    string ( Duration format)

    sessions.read data at a timestamp >= NOW - maxStaleness seconds. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client's local clock is substantially skewed from Cloud Spanner commit timestamps.

    Useful for reading the freshest data available at a nearby replica, while bounding the possible staleness if the local replica has fallen behind.

    Note that this option can only be used in single-use transactions.

    A duration in seconds with up to nine fractional digits, ending with ' s '. Example: "3.5s" .

    readTimestamp

    string ( Timestamp format)

    Executes all reads at the given timestamp. Unlike other modes, reads at a specific timestamp are repeatable; the same read at the same timestamp always returns the same data. If the timestamp is in the future, the read is blocked until the specified timestamp, modulo the read's deadline.

    Useful for large scale consistent reads such as mapreduces, or for coordinating many reads against a consistent snapshot of the data.

    A timestamp in RFC3339 UTC "Zulu" format, accurate to nanoseconds. Example: "2014-10-02T15:01:23.045123456Z" .

    Uses RFC 3339, where generated output will always be Z-normalized and uses 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted. Examples: "2014-10-02T15:01:23Z" , "2014-10-02T15:01:23.045123456Z" or "2014-10-02T15:01:23+05:30" .

    exactStaleness

    string ( Duration format)

    Executes all reads at a timestamp that is exactStaleness old. The timestamp is chosen soon after the read is started.

    Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client's local clock is substantially skewed from Cloud Spanner commit timestamps.

    Useful for reading at nearby replicas without the distributed timestamp negotiation overhead of maxStaleness .

    A duration in seconds with up to nine fractional digits, ending with ' s '. Example: "3.5s" .

    IsolationLevel

    IsolationLevel is used when setting the isolation level for a transaction.

    Enums
    ISOLATION_LEVEL_UNSPECIFIED

    Default value.

    If the value is not specified, the SERIALIZABLE isolation level is used.
    SERIALIZABLE All transactions appear as if they executed in a serial order, even if some of the reads, writes, and other operations of distinct transactions actually occurred in parallel. Spanner assigns commit timestamps that reflect the order of committed transactions to implement this property. Spanner offers a stronger guarantee than serializability called external consistency. For more information, see TrueTime and external consistency .
    REPEATABLE_READ

    All reads performed during the transaction observe a consistent snapshot of the database, and the transaction is only successfully committed in the absence of conflicts between its updates and any concurrent updates that have occurred since that snapshot. Consequently, in contrast to SERIALIZABLE transactions, only write-write conflicts are detected in snapshot transactions.

    This isolation level does not support read-only and partitioned DML transactions.

    When REPEATABLE_READ is specified on a read-write transaction, the locking semantics default to OPTIMISTIC .
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