Transaction Serialization Methods

Replication Server provides four different serialization methods for specifying the level of parallelization. The serialization method you choose depends on your replication environment, and the amount of contention you expect between parallel threads.

Each serialization method defines the degree to which a transaction can start before it must wait for the previous transaction to commit.

Use the dsi_partitioning_rule parameter to reduce the probability of contention without reducing the degree of parallelism assigned by the serialization method.

alter connection to SYDNEY_DS.pubs2
 set dsi_serialization_method to 'wait_for_commit'

While providing commit consistency, the serialization method defines whether the beginning of the transaction waits for the previous transaction to become ready to commit or if the beginning of the transaction can be processed earlier.

• no_wait
  The no_wait method instructs the DSI to initiate the next transaction without waiting for the previous transaction to commit.
• wait_for_start
  wait_for_start specifies that a transaction can start as soon as the transaction scheduled to commit immediately before it has started.
• wait_for_commit
  In wait_for_commit method, the next thread’s transaction group is not sent for processing until the previous transaction has processed successfully and the commit is being sent.
• wait_after_commit
  wait_after_commit specifies that a transaction cannot start until the transaction scheduled to commit immediately preceding it has committed completely.