Horton

Re: pg_receivewal starting position

Ronan Dunklau <ronan.dunklau@aiven.io>

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From: Ronan Dunklau <ronan.dunklau@aiven.io>
To: Michael Paquier <michael@paquier.xyz>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2021-10-20T12:58:26Z
Lists: pgsql-hackers

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Le mercredi 20 octobre 2021 11:40:18 CEST, vous avez écrit :
> > +# Setup the slot, and connect to it a first time
> > +$primary->run_log(
> > +   [ 'pg_receivewal', '--slot', $slot_name, '--create-slot' ],
> > +   'creating a replication slot');
> > +$primary->psql('postgres',
> > +   'INSERT INTO test_table VALUES (generate_series(1,100));');
> > +$primary->psql('postgres', 'SELECT pg_switch_wal();');
> > +$nextlsn =
> > +  $primary->safe_psql('postgres', 'SELECT pg_current_wal_insert_lsn();');
> > +chomp($nextlsn);
> > Wouldn't it be simpler to use CREATE_REPLICATION_SLOT with RESERVE_WAL
> > here, rather than going through pg_receivewal?  It seems to me that
> > this would be cheaper without really impacting the coverage.
> 
> You're right, we can skip two invocations of pg_receivewal like this (for
> the slot creation + for starting the slot a first time).

After sending the previous patch suite, I figured it would be worthwhile to 
also have tests covering timeline switches, which was not covered before.
So please find attached a new version with an additional patch for those tests, 
covering both  "resume from last know archive" and "resume from the 
replication slots position" cases.

-- 
Ronan Dunklau

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()