Horton

Re: pg_receivewal starting position

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Ronan Dunklau <ronan.dunklau@aiven.io>
Cc: pgsql-hackers@lists.postgresql.org, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2021-10-23T07:44:00Z
Lists: pgsql-hackers

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On Thu, Oct 21, 2021 at 10:36:42AM +0200, Ronan Dunklau wrote:
> Done. I haven't touched the timeline switch test patch for now, but I still 
> include it here for completeness.

Thanks.  I have applied and back-patched 0001, then looked again at
0002 that adds READ_REPLICATION_SLOT:
- Change the TLI to use int8 rather than int4, so as we will always be
right with TimelineID which is unsigned (this was discussed upthread
but I got back on it after more thoughts, to avoid any future
issues).
- Added an extra initialization for the set of Datum values, just as
an extra safety net.
- There was a bug with the timeline returned when executing the
command while in recovery as ThisTimeLineID is 0 in the context of a
standby, but we need to support the case of physical slots even when
streaming archives from a standby.  The fix is similar to what we do
for IDENTIFY_SYSTEM, where we need to use the timeline currently
replayed from GetXLogReplayRecPtr(), before looking at the past
timeline history using restart_lsn and the replayed TLI.

With that in place, I think that we are good now for this part.
--
Michael

Commits

  1. Add TAP test for pg_receivewal with timeline switch

  2. Speed up TAP tests of pg_receivewal

  3. Allow pg_receivewal to stream from a slot's restart LSN

  4. Add replication command READ_REPLICATION_SLOT

  5. doc: Describe calculation method of streaming start for pg_receivewal

  6. Add PostgresNode::command_fails_like()