postgres.git / summary / log / commit / refs

commit    27d04ed5310ad33dd3364322ae53ea685b28a8b6
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Thu Jan 18 10:30:53 2024 +0000
First released in: 17.0

    Rework text in replication slots documentation
    
    This is cosmetic, so no backpatch.
    
    Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
    Discussion: https://postgr.es/m/20230413111838.e7yxke2dtwrxw3qy@alvherre.pgsql
    Discussion: https://postgr.es/m/202401151537.ryhysqfncs6d@alvherre.pgsql


doc/src/sgml/high-availability.sgml | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml index 9dd52ff2750..236c0af65fb 100644 --- a/doc/src/sgml/high-availability.sgml +++ b/doc/src/sgml/high-availability.sgml @@ -924,7 +924,8 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass' <secondary>streaming replication</secondary> </indexterm> <para> - Replication slots provide an automated way to ensure that the primary does + Replication slots provide an automated way to ensure that the + primary server does not remove WAL segments until they have been received by all standbys, and that the primary does not remove rows which could cause a <link linkend="hot-standby-conflict">recovery conflict</link> even when the @@ -935,21 +936,28 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass' of old WAL segments using <xref linkend="guc-wal-keep-size"/>, or by storing the segments in an archive using <xref linkend="guc-archive-command"/> or <xref linkend="guc-archive-library"/>. - However, these methods often result in retaining more WAL segments than + A disadvantage of these methods is that they + often result in retaining more WAL segments than required, whereas replication slots retain only the number of segments - known to be needed. On the other hand, replication slots can retain so - many WAL segments that they fill up the space allocated - for <literal>pg_wal</literal>; - <xref linkend="guc-max-slot-wal-keep-size"/> limits the size of WAL files - retained by replication slots. + known to be needed. </para> <para> Similarly, <xref linkend="guc-hot-standby-feedback"/> on its own, without also using a replication slot, provides protection against relevant rows being removed by vacuum, but provides no protection during any time period - when the standby is not connected. Replication slots overcome these - disadvantages. + when the standby is not connected. </para> + + <caution> + <para> + Beware that replication slots can cause the server to retain so + many WAL segments that they fill up the space allocated for + <literal>pg_wal</literal>. + <xref linkend="guc-max-slot-wal-keep-size"/> can be used to limit the size + of WAL files retained by replication slots. + </para> + </caution> + <sect3 id="streaming-replication-slots-manipulation"> <title>Querying and Manipulating Replication Slots</title> <para> [parent: ed1e0a65127a]