The failover slots ensure a seamless transition of a subscriber after the
standby is promoted. But the docs for it also explain the behavior of
asynchronous replication which can confuse the readers.
Reported-by: Masahiro Ikeda
Backpatch-through: 17
Discussion: https://postgr.es/m/OS3PR01MB6390B660F4198BB9745E0526B18B2@OS3PR01MB6390.jpnprd01.prod.outlook.com
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
parameter ensures a seamless transition of those subscriptions after the
standby is promoted. They can continue subscribing to publications on the
- new primary server without losing data. Note that in the case of
- asynchronous replication, there remains a risk of data loss for transactions
- committed on the former primary server but have yet to be replicated to the new
- primary server.
+ new primary server.
</para>
<para>
If all the slots are present on the standby server and the result
(<literal>failover_ready</literal>) of the above SQL query is true, then
existing subscriptions can continue subscribing to publications now on the
- new primary server without losing data.
+ new primary server.
</para>
</sect1>