Horton

Re: Minimal logical decoding on standbys

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Andres Freund <andres@anarazel.de>
Cc: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Jeff Davis <pgsql@j-davis.com>, Robert Haas <robertmhaas@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Amit Khandekar <amitdkhan.pg@gmail.com>, fabriziomello@gmail.com, tushar <tushar.ahuja@enterprisedb.com>, Rahila Syed <rahila.syed@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2023-04-12T05:07:44Z
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.

On Tue, Apr 11, 2023 at 01:10:57PM -0700, Andres Freund wrote:
> On 2023-04-11 11:04:50 +0200, Drouvot, Bertrand wrote:
> > On 4/11/23 10:55 AM, Drouvot, Bertrand wrote:
> > > I think we might want to add:
> > > 
> > > $node_primary->wait_for_replay_catchup($node_standby);
> > > 
> > > before calling the slot creation.

> Pushed. Seems like a clear race in the test, so I didn't think it was worth
> waiting for testing it on hoverfly.

We'll see what happens in the next run.

> I think we should lower the log level, but perhaps wait for a few more cycles
> in case there are random failures?

Fine with me.

> I wonder if we should make the connections in poll_query_until to reduce
> verbosity - it's pretty annoying how much that can bloat the log. Perhaps also
> introduce some backoff? It's really annoying to have to trawl through all
> those logs when there's a problem.

Agreed.  My ranked wish list for poll_query_until is:

1. Exponential backoff
2. Closed-loop time control via Time::HiRes or similar, instead of assuming
   that ten loops complete in ~1s.  I've seen the loop take 3x as long as the
   intended timeout.
3. Connect less often than today's once per probe