spock.sync_event

The spock.sync_event() function creates a synchronization event in the replication stream and returns its Log Sequence Number (LSN).

Synopsis

spock.sync_event()

Returns

The function returns the Log Sequence Number (LSN) of the created synchronization event as pg_lsn.

Description

The spock.sync_event() function creates a synchronization event in the replication stream and returns its LSN.

This function inserts a special synchronization marker into the logical replication stream at the current write position. The returned LSN identifies this marker's location in the write-ahead log and can be used with functions like spock.wait_slot_confirm_lsn() to verify that subscribers have processed replication up to this point.

Synchronization events are useful for coordinating activities across multiple nodes in a replication topology. By creating a sync event on a provider and then waiting for subscribers to reach that LSN, you can ensure all nodes have processed a consistent set of changes before proceeding with operations that depend on synchronized state.

The sync event itself does not contain data or modify any tables; the event serves purely as a coordination marker in the replication stream.

This function modifies the replication stream by inserting a sync marker.

Arguments

The function takes no arguments.

Example

In the following example, the spock.sync_event() function creates a synchronization event and returns the LSN:

SELECT spock.sync_event();
-[ RECORD 1 ]---------
sync_event | 0/333F410

For more information about using synchronization events with Zero-Downtime Add Node, see the ZODAN Tutorial.