Horton

Re: Minimal logical decoding on standbys

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: "Drouvot, Bertrand" <bertranddrouvot.pg@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: 2023-04-08T03:45:05Z
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 Fri, Apr 7, 2023 at 11:42 PM Andres Freund <andres@anarazel.de> wrote:
>
> On 2023-04-07 08:47:57 -0700, Andres Freund wrote:
> > Integrated all of these.
>
> Here's my current version. Changes:
> - Integrated Bertrand's changes
> - polished commit messages of 0001-0003
> - edited code comments for 0003, including
>   InvalidateObsoleteReplicationSlots()'s header
> - added a bump of SLOT_VERSION to 0001
> - moved addition of pg_log_standby_snapshot() to 0007
> - added a catversion bump for pg_log_standby_snapshot()
> - moved all the bits dealing with procsignals from 0003 to 0004, now the split
>   makes sense IMO
> - combined a few more sucessive ->safe_psql() calls
>

The new approach for invalidation looks clean. BTW, I see minor
inconsistency in the following two error messages (errmsg):

if (MyReplicationSlot->data.invalidated == RS_INVAL_WAL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("can no longer get changes from replication slot \"%s\"",
NameStr(MyReplicationSlot->data.name)),
errdetail("This slot has been invalidated because it exceeded the
maximum reserved size.")));

if (MyReplicationSlot->data.invalidated != RS_INVAL_NONE)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("cannot read from logical replication slot \"%s\"",
NameStr(MyReplicationSlot->data.name)),
errdetail("This slot has been invalidated because it was conflicting
with recovery.")));

Won't it be better to keep the same errmsg in the above two cases?

-- 
With Regards,
Amit Kapila.