From: Jesper Pedersen <jesper.pedersen@redhat.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: pg_receivewal documentation
Date: Fri, 19 Jul 2019 13:01:27 -0400
Message-ID: <ab8f78b5-4b9f-e31d-daee-c398424fae8c@redhat.com> (raw)
In-Reply-To: <20190719010903.GC1859@paquier.xyz>
References: <54779de5-f922-c0cf-629d-b582eded7265@redhat.com>
<20190716050555.GA1439@paquier.xyz>
<ebed4b9043b222d486ea3f0e44e7dcd242a80781.camel@cybertec.at>
<65c3ecdf-8995-34cb-83c4-50068877e632@redhat.com>
<20190717013835.GA2130@paquier.xyz>
<44e51f9f60abb872854879c91da0ed3b67a6ba95.camel@cybertec.at>
<20190717080424.GB20614@paquier.xyz>
<7eaf748c-3f40-c994-0eb3-7d87709588d0@redhat.com>
<184780f1f90a31c4c8b53f0e6328bf5aaae4f786.camel@cybertec.at>
<e62fcdf7-556c-d4e1-73cd-fc325f89374d@redhat.com>
<20190719010903.GC1859@paquier.xyz>
Hi,
On 7/18/19 9:09 PM, Michael Paquier wrote:
>> pg_receivewal -D /tmp/wal -S replica1 --synchronous -h localhost -p 5432 -U
>> repluser -W
>> psql -c 'SELECT * FROM pg_stat_replication;' postgres
>> psql -c 'SELECT * FROM pg_replication_slots;' postgres
>> psql -c 'CREATE DATABASE test' postgres
>>
>> In what scenarios do you see 'on' working ?
>
> Because the code says so, "on" is an alias for "remote_flush" (which
> is not user-visible by the way):
> src/include/access/xact.h:#define SYNCHRONOUS_COMMIT_ON
> SYNCHRONOUS_COMMIT_REMOTE_FLUSH
>
> And if you do that it works fine (pg_receivewal --synchronous runs in
> the background and I created a dummy table):
> =# SELECT application_name, sync_state, flush_lsn, replay_lsn FROM
> pg_stat_replication;
> application_name | sync_state | flush_lsn | replay_lsn
> ------------------+------------+-----------+------------
> pg_receivewal | sync | 0/15E1F88 | null
> (1 row)
> =# set synchronous_commit to on ;
> SET
> =# insert into aa values (2);
> INSERT 0 1
>
I forgot to use pg_receivewal -d with application_name instead of -h -p -U.
Maybe we should have an explicit option for that, but that is a separate
thread.
Best regards,
Jesper
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To: pgsql-hackers@postgresql.org
Cc: jesper.pedersen@redhat.com, michael@paquier.xyz, laurenz.albe@cybertec.at, alvherre@2ndquadrant.com
Subject: Re: pg_receivewal documentation
In-Reply-To: <ab8f78b5-4b9f-e31d-daee-c398424fae8c@redhat.com>
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