Class ReadWrite (3.58.0)

Version latest

• 3.58.0 (latest)
• 3.57.0
• 3.56.0
• 3.55.0
• 3.54.0
• 3.53.0
• 3.52.0
• 3.51.0
• 3.50.1
• 3.46.0
• 3.45.0
• 3.44.0
• 3.43.0
• 3.42.0
• 3.41.0
• 3.40.1
• 3.39.0
• 3.38.0
• 3.37.0
• 3.36.0
• 3.35.1
• 3.34.0
• 3.33.0
• 3.32.0
• 3.31.0
• 3.30.0
• 3.29.0
• 3.28.0
• 3.27.1
• 3.26.0
• 3.25.0
• 3.24.0
• 3.23.0
• 3.22.2
• 3.21.0
• 3.20.0
• 3.19.0
• 3.18.0
• 3.17.0
• 3.16.0
• 3.15.1
• 3.14.1
• 3.13.0
• 3.12.1
• 3.11.1
• 3.10.0
• 3.9.0
• 3.8.0
• 3.7.0
• 3.6.0
• 3.5.0
• 3.4.0
• 3.3.0
• 3.2.0
• 3.1.0
• 3.0.0
• 2.1.1
• 2.0.0
• 1.19.3
• 1.18.0
• 1.17.1
• 1.16.0
• 1.15.1
• 1.14.0
• 1.13.0
• 1.12.0
• 1.11.0
• 1.10.0

ReadWrite(mapping=None, *, ignore_unknown_fields=False, **kwargs)

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

Attributes
Name	Description
read_lock_mode	google.cloud.spanner_v1.types.TransactionOptions.ReadWrite.ReadLockMode Read lock mode for the transaction.
multiplexed_session_previous_transaction_id	bytes 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.

Classes

ReadLockMode

ReadLockMode(value)

ReadLockMode is used to set the read lock mode for read-write transactions.

    - If isolation level is
      `REPEATABLE_READ][google.spanner.v1.TransactionOptions.IsolationLevel.REPEATABLE_READ]`,
      then it is an error to specify `read_lock_mode`. Locking
      semantics default to `OPTIMISTIC`. No validation checks
      are done for reads, except to validate that the data that
      was served at the snapshot time is unchanged at commit
      time in the following cases:

      1. reads done as part of queries that use
         `SELECT FOR UPDATE`
      2. reads done as part of statements with a
         `LOCK_SCANNED_RANGES` hint
      3. reads done as part of DML statements

    - At all other isolation levels, if `read_lock_mode` is
      the default value, then pessimistic read locks are used.
PESSIMISTIC (1):
    Pessimistic lock mode.

    Read locks are acquired immediately on read. Semantics
    described only applies to
    `SERIALIZABLE][google.spanner.v1.TransactionOptions.IsolationLevel.SERIALIZABLE]`
    isolation.
OPTIMISTIC (2):
    Optimistic lock mode.

    Locks for reads within the transaction are not acquired on
    read. Instead the locks are acquired on a commit to validate
    that read/queried data has not changed since the transaction
    started. Semantics described only applies to
    `SERIALIZABLE][google.spanner.v1.TransactionOptions.IsolationLevel.SERIALIZABLE]`
    isolation.