Horton

Re: Minimal logical decoding on standbys

Ronan Dunklau <ronan.dunklau@aiven.io>

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From: Ronan Dunklau <ronan.dunklau@aiven.io>
To: Ibrar Ahmed <ibrar.ahmad@gmail.com>, Amit Khandekar <amitdkhan.pg@gmail.com>, pgsql-hackers@lists.postgresql.org, "Drouvot, Bertrand" <bdrouvot@amazon.com>
Cc: Andres Freund <andres@anarazel.de>, fabriziomello@gmail.com, Alvaro Herrera <alvherre@2ndquadrant.com>, tushar <tushar.ahuja@enterprisedb.com>, "[pgdg] Robert Haas" <robertmhaas@gmail.com>, Rahila Syed <rahila.syed@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-08-02T15:47:14Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Reduce the log level in 035_standby_logical_decoding.pl.

  2. 035_standby_logical_decoding: Add missing waits for replication

  3. For cascading replication, wake physical and logical walsenders separately

  4. Handle logical slot conflicts on standby

  5. Support invalidating replication slots due to horizon and wal_level

  6. Prevent use of invalidated logical slot in CreateDecodingContext()

  7. Replace replication slot's invalidated_at LSN with an enum

  8. Pass down table relation into more index relation functions

  9. Assert only valid flag bits are passed to visibilitymap_set()

  10. Remove unused _bt_delitems_delete() argument.

  11. Add xl_btree_delete optimization.

Le lundi 2 août 2021, 17:31:46 CEST Drouvot, Bertrand a écrit :
> > I think the beahviour when dropping a database on the primary should be
> > documented, and proper procedures for handling it correctly should be
> > suggested.
> > 
> > Something along the lines of:
> > 
> > "If a database is dropped on the primary server, the logical replication
> > slot on the standby will be dropped as well. This means that you should
> > ensure that the client usually connected to this slot has had the
> > opportunity to stream the latest changes before the database is dropped."
> 
> I am not sure we should highlight this as part of this patch.
> 
> I mean, the same would currently occur on a non standby if you drop a
> database that has a replication slot linked to it.

The way I see it, the main difference is that you drop an additional object on 
the standby, which doesn't exist and that you don't necessarily have any 
knowledge of on the primary. As such, I thought it would be better to be 
explicit about it to warn users of that possible case.


Regards,

--
Ronan Dunklau