Snapshot Synchronization Functions

Snapshot synchronization functions save the current snapshot and return its identifier.

pg_export_snapshot()

Description: Saves the current snapshot and returns its identifier.

Return type: text

Note:pg_export_snapshot saves the current snapshot and returns a text string identifying the snapshot. This string must be passed to clients that want to import the snapshot. A snapshot can be imported when the set transaction snapshot snapshot_id; command is executed. Doing so is possible only when the transaction is set to the SERIALIZABLE or REPEATABLE READ isolation level. MogDB does not support these two isolation levels currently. The output of the function cannot be used as the input of set transaction snapshot.

pg_export_snapshot_and_csn()

Description: Saves the current snapshot and returns its identifier. Compared with pg_export_snapshot(), pg_export_snapshot() returns a CSN, indicating the CSN of the current snapshot.

Return type: text