@@ -924,7 +924,8 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass'
924924 <secondary>streaming replication</secondary>
925925 </indexterm>
926926 <para>
927- Replication slots provide an automated way to ensure that the primary does
927+ Replication slots provide an automated way to ensure that the
928+ primary server does
928929 not remove WAL segments until they have been received by all standbys,
929930 and that the primary does not remove rows which could cause a
930931 <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'
935936 of old WAL segments using <xref linkend="guc-wal-keep-size"/>, or by
936937 storing the segments in an archive using
937938 <xref linkend="guc-archive-command"/> or <xref linkend="guc-archive-library"/>.
938- However, these methods often result in retaining more WAL segments than
939+ A disadvantage of these methods is that they
940+ often result in retaining more WAL segments than
939941 required, whereas replication slots retain only the number of segments
940- known to be needed. On the other hand, replication slots can retain so
941- many WAL segments that they fill up the space allocated
942- for <literal>pg_wal</literal>;
943- <xref linkend="guc-max-slot-wal-keep-size"/> limits the size of WAL files
944- retained by replication slots.
942+ known to be needed.
945943 </para>
946944 <para>
947945 Similarly, <xref linkend="guc-hot-standby-feedback"/> on its own, without
948946 also using a replication slot, provides protection against relevant rows
949947 being removed by vacuum, but provides no protection during any time period
950- when the standby is not connected. Replication slots overcome these
951- disadvantages.
948+ when the standby is not connected.
952949 </para>
950+
951+ <caution>
952+ <para>
953+ Beware that replication slots can cause the server to retain so
954+ many WAL segments that they fill up the space allocated for
955+ <literal>pg_wal</literal>.
956+ <xref linkend="guc-max-slot-wal-keep-size"/> can be used to limit the size
957+ of WAL files retained by replication slots.
958+ </para>
959+ </caution>
960+
953961 <sect3 id="streaming-replication-slots-manipulation">
954962 <title>Querying and Manipulating Replication Slots</title>
955963 <para>