Hi all,
The documentation does not explain at all what means "sync" or "async"
on pg_stat_replication. The paragraph "Planning for high availability"
mentions "catchup" and "streaming", but it does not say that users can
refer to it directly in pg_stat_replication.
Thoughts about the patch attached to add a couple of sentences in
"Planning for high availability"? We could as well mention it directly
in the page of pg_stat_replication but this information seems more
suited if located in the HA section.
Thanks,
--
Michael
diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml
index 5bedaf2..5ef6aa9 100644
--- a/doc/src/sgml/high-availability.sgml
+++ b/doc/src/sgml/high-availability.sgml
@@ -1235,6 +1235,8 @@ synchronous_standby_names = '2 (s1, s2, s3)'
will increase according to the length of time the standby has been down.
The standby is only able to become a synchronous standby
once it has reached <literal>streaming</> state.
+ This is directly reported by the system view
+ <literal>pg_stat_replication</> with the field <literal>state</>.
</para>
<para>
@@ -1259,6 +1261,12 @@ synchronous_standby_names = '2 (s1, s2, s3)'
</para>
<para>
+ Asynchronous standbys are reported as <literal>async</> in the system
+ view <structname>pg_stat_replication</> with the field
+ <structfield>sync_state</>, and synchronous standbys as <literal>sync</>.
+ </para>
+
+ <para>
If the primary is isolated from remaining standby servers you should
fail over to the best candidate of those other remaining standby servers.
</para>
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