With the basic output plugin callbacks (eg., begin_cb, change_cb, commit_cb and message_cb) two-phase commit commands like PREPARE TRANSACTION, COMMIT PREPARED and ROLLBACK PREPARED are not decoded. While the PREPARE TRANSACTION is ignored, COMMIT PREPARED is decoded as a COMMIT and ROLLBACK PREPARED is decoded as a ROLLBACK.

To support the streaming of two-phase commands, an output plugin needs to provide additional callbacks. There are multiple two-phase commit callbacks that are required, (begin_prepare_cb, prepare_cb, commit_prepared_cb, rollback_prepared_cb and stream_prepare_cb) and an optional callback (filter_prepare_cb).

If the output plugin callbacks for decoding two-phase commit commands are provided, then on PREPARE TRANSACTION, the changes of that transaction are decoded, passed to the output plugin, and the prepare_cb callback is invoked. This differs from the basic decoding setup where changes are only passed to the output plugin when a transaction is committed. The start of a prepared transaction is indicated by the begin_prepare_cb callback.

When a prepared transaction is rollbacked using the ROLLBACK PREPARED, then the rollback_prepared_cb callback is invoked and when the prepared transaction is committed using COMMIT PREPARED, then the commit_prepared_cb callback is invoked.

Optionally the output plugin can specify a name pattern in the filter_prepare_cb and transactions with gid containing that name pattern will not be decoded as a two-phase commit transaction.