This article was originally published on April 13, 2023
WHAT’S NEW
This announcement is notifying you of a new software release by EDB named PG Failover Slots (pg_failover_slots). This database extension is released as open source software under the PostgreSQL LICENSE and is for customers who have logical replication publications on Postgres databases that are also part of a Streaming Replication architecture.
PG Failover Slots avoids the need for logical replication subscribers to reseed their logical replication tables when the logical replication publisher is part of a physical streaming replication architecture and a new Standby gets promoted to Primary.
Since the replication slot used by logical replication is only maintained on the Primary node, downstream subscribers will not receive any new changes from the newly promoted Primary until the slot is created on the newly promoted Primary. Picking up logical replication changes from the newly promoted standby is unsafe because the information that includes which data a subscriber has confirmed receiving and which log data still needs to be retained for the subscriber will have been lost, resulting in an unknown gap in data. PG Failover Slots makes logical replication slots usable across a physical failover via the following features in the initial release:
- Copies any missing replication slots from the primary to the standby
- Removes any slots from the standby that aren't found on the primary
- Periodically synchronizes the position of slots on the standby based on the primary
- Ensures that selected standbys receive data before any of the logical slot walsenders can send data to consumers
Release notes for PG Failover Slots will also be published in EDB Docs.
TELL ME MORE
For more details, please review the PG Failover Slots documentation:
PG Failover Slots Documentation
IS THIS FOR ME?
This announcement is for EDB customers who have a subscription and are either currently using or are interested in logical replication with a physical replication architecture.
HOW TO GET THE SOFTWARE
EDB Failover Slots is available from the EDB website https://www.enterprisedb.com/downloads.
To request the credentials required to access EDB repositories, visit Create new account.
TROUBLESHOOTING
If you experience any problems around the installation, migration, upgrade or general use of your EDB software, please contact our Technical Support teams. Customers may reach us at https://techsupport.enterprisedb.com, and we're also available 24x7 via email and phone at the details below:
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