AutoCommitTxn Execution Property

Since user level commands may execute multiple source commands, users can specify the AutoCommitTxn execution property to control the transactional behavior of a user command when not in a local or global transaction.

Table 1. AutoCommitTxn Settings
Setting Description

OFF

Do not wrap each command in a transaction. Individual source commands may commit or rollback regardless of the success or failure of the overall command.

ON

Wrap each command in a transaction. This mode is the safest, but may introduce performance overhead.

DETECT

This is the default setting. Will automatically wrap commands in a transaction, but only if the command seems to be transactionally unsafe.

The concept of command safety with respect to a transaction is determined by Teiid based upon command type, the transaction isolation level, and available metadata. A wrapping transaction is not needed if:

  • If a user command is fully pushed to the source.

  • If the user command is a SELECT (including XML) and the transaction isolation is not REPEATABLE_READ nor SERIALIABLE.

  • If the user command is a stored procedure and the transaction isolation is not REPEATABLE_READ nor SERIALIABLE and the Updating Model Count is zero.

The update count may be set on all procedures as part of the procedure metadata in the model.

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