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doc: update "standby follow" reference

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Add note about handling of timeline forks etc.
This commit is contained in:
Ian Barwick
2019-02-12 16:36:54 +09:00
parent 790bec21dd
commit 7b85cb9f12
1 changed files with 34 additions and 1 deletions
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35
doc/repmgr-standby-follow.sgml
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@@ -146,6 +146,39 @@
</variablelist>
</refsect1>
<refsect1>
<title>Execution</title>
<para>
Execute with the <literal>--dry-run</literal> option to test the follow operation as
far as possible, without actually changing the status of the node.
</para>
<para>
Note that &repmgr; will first attempt to determine whether the standby
(&quot;follow candidate&quot;) is capable of following the
new upstream node (&quot;follow target&quot;).
</para>
<para>
If, for example, the new upstream node has diverged from this node's timeline,
for example if the new upstream node was promoted to primary while this node
was still attached to the original primary, it will <emphasis>not</emphasis>
be possible to follow the new upstream node, and &repmgr; will emit an error
message like this:
<programlisting>
ERROR: this node cannot attach to follow target node 3
DETAIL: follow target server's timeline 2 forked off current database system timeline 1 before current recovery point 0/6108880</programlisting>
</para>
<para>
In this case, it may be possible to have this node follow the new upstream
using <command><link linkend="repmgr-node-rejoin">repmgr node rejoin</link></command>
with the <option>--force-rewind</option> to execute <command>pg_rewind</command>.
This does mean that transacations which exist on this node, but not the new upstream,
will be lost.
</para>
</refsect1>
<refsect1>
<title>Exit codes</title>
<para>
@@ -210,7 +243,7 @@
A <literal>standby_follow</literal> <link linkend="event-notifications">event notification</link> will be generated.
</para>
<para>
If provided, &repmgr; will substitute the placeholders <literal>%p</literal> with the node ID of the primary
If provided, &repmgr; will substitute the placeholders <literal>%p</literal> with the node ID of the node
being followed, <literal>%c</literal> with its <literal>conninfo</literal> string, and
<literal>%a</literal> with its node name.
</para>