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.
<scroll-title title="AutoCommitTxn Settings"></scroll-title>
|
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.