diff options
| author | Michael Paquier | 2019-07-24 02:26:52 +0000 |
|---|---|---|
| committer | Michael Paquier | 2019-07-24 02:26:52 +0000 |
| commit | 4a25ed16400c01fb64c23d2d6f413af95b4e28f8 (patch) | |
| tree | ab1f67d03ae9c4a0f6ff6603618fe5eed03cb7ca | |
| parent | c6f961bbbb202bd99053524efdd40fcd70e0aa4f (diff) | |
Doc: Clarify interactions of pg_receivexlog with remote_apply
Using pg_receivexlog with synchronous_commit = remote_apply set in the
backend is incompatible if pg_receivexlog is a synchronous standby as it
never applies WAL, so document this problem and solutions to it.
Backpatch to 9.6, where remote_apply has been added.
Author: Robert Haas, Jesper Pedersen
Reviewed-by: Laurenz Albe, Álvaro Herrera, Michael Paquier
Discussion: https://postgr.es/m/1427a2d3-1e51-9335-1931-4f8853d90d5e@redhat.com
Backpatch-through: 9.6
| -rw-r--r-- | doc/src/sgml/ref/pg_receivexlog.sgml | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/doc/src/sgml/ref/pg_receivexlog.sgml b/doc/src/sgml/ref/pg_receivexlog.sgml index bfa055b58b3..4cfc490e0a8 100644 --- a/doc/src/sgml/ref/pg_receivexlog.sgml +++ b/doc/src/sgml/ref/pg_receivexlog.sgml @@ -52,7 +52,17 @@ PostgreSQL documentation Unlike the WAL receiver of a PostgreSQL standby server, <application>pg_receivexlog</> by default flushes WAL data only when a WAL file is closed. The option <option>--synchronous</> must be specified to flush WAL data - in real time. + in real time. Since <application>pg_receivexlog</application> does not + apply WAL, you should not allow it to become a synchronous standby when + <xref linkend="guc-synchronous-commit"/> equals + <literal>remote_apply</literal>. If it does, it will appear to be a + standby that never catches up, and will cause transaction commits to + block. To avoid this, you should either configure an appropriate value + for <xref linkend="guc-synchronous-standby-names"/>, or specify + <varname>application_name</varname> for + <application>pg_receivexlog</application> that does not match it, or + change the value of <varname>synchronous_commit</varname> to + something other than <literal>remote_apply</literal>. </para> <para> |