Logical replication

[gbartolini]

Declarative way to publish changes to one or more tables using logical replication (publications), as well as to subscribe to any Postgres 10+ publication (subscriptions) and consume those events.

[ns-gzhang]

Any plan to support Debezium for CDC, which requires logical replication I believe?

[abratanich]

Greetings. is it planned to add such support at the HA level in the near future?

[ns-jhu]

do we know when this feature is available ? without this , software such as debezium doesn't work well when postgres failover happens. In Zalando, we can config the replication_slot in the secondary, which is called permanent replication_slot, to enable debezium to work with postgres change event streaming seamlessly when failover happens. that is a highly desirable feature.

I checked version 1.18, and see this:

2		ctx,
3		`SELECT slot_name, slot_type, active, coalesce(restart_lsn::TEXT, '') AS restart_lsn FROM pg_replication_slots
4            WHERE NOT temporary AND slot_name ^@ $1 AND slot_type = 'physical'`,
5		config.HighAvailability.GetSlotPrefix(),
6	)

where only physical replication slots are supported, and it demands the slot to be prefixed with __cnpg__, this does not work well with debezium, as it is shown as this:

Unmanaged Replication Slot Status
Slot Name  Slot Type  Database  Active  Restart LSN  XMin  Catalog XMin  Datoid  Plugin    Wal Status  Safe Wal Size
---------  ---------  --------  ------  -----------  ----  ------------  ------  ------    ----------  -------------
debezium   logical    app       true    0/1600A540         1758          16385   pgoutput  reserved    NULL

[MathCharton]

Hello @mnencia !
Can u confirm that HA replication_slot feature only work with physical replication slots ???
Thanks

[ns-jhu]

Here is the code:

cloudnative-pg/internal/management/controller/slots/infrastructure/postgresmanager.go

Line 62 in 56aea79

WHERE NOT temporary AND slot_name ^@ $1 AND slot_type = 'physical'`,

[ns-jhu]

we also need to remove the restriction that the replication slot has to start "cnpg" , as debezium 's replication slot is named "debezium"

[awebneck]

I've seen elsewhere that using the pg_failover_slots should support logical replication in CNPG, but after multiple attempts trying to get debezium to such a cluster I still don't seem to be able to establish things. What is the status of this issue?

[abratanich]

Everything works fine for me, show me the settings