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