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Add a failover option to subscriptions.

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This commit introduces a new subscription option named 'failover', which
provides users with the ability to set the failover property of the
replication slot on the publisher when creating or altering a
subscription.

This uses the replication commands introduced by commit 7329240437 to
enable the failover option for a logical replication slot.

If the failover option is set to true, the associated replication slots
(i.e. the main slot and the table sync slots) in the upstream database are
enabled to be synchronized to the standbys. Note that the capability to
sync the replication slots will be added in subsequent commits.

Thanks to Masahiko Sawada for the design inputs.

Author: Shveta Malik, Hou Zhijie, Ajin Cherian
Reviewed-by: Peter Smith, Bertrand Drouvot, Dilip Kumar, Masahiko Sawada, Nisha Moond, Kuroda Hayato, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
This commit is contained in:
Amit Kapila
2024-01-30 16:31:09 +05:30
parent b527ebc1d3
commit 776621a5e4
21 changed files with 412 additions and 108 deletions
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11
doc/src/sgml/catalogs.sgml
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@ -8000,6 +8000,17 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
</para></entry>
</row>
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>subfailover</structfield> <type>bool</type>
</para>
<para>
If true, the associated replication slots (i.e. the main slot and the
table sync slots) in the upstream database are enabled to be
synchronized to the standbys
</para></entry>
</row>
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>subconninfo</structfield> <type>text</type>

25
doc/src/sgml/ref/alter_subscription.sgml
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@ -226,10 +226,31 @@ ALTER SUBSCRIPTION <replaceable class="parameter">name</replaceable> RENAME TO <
<link linkend="sql-createsubscription-params-with-streaming"><literal>streaming</literal></link>,
<link linkend="sql-createsubscription-params-with-disable-on-error"><literal>disable_on_error</literal></link>,
<link linkend="sql-createsubscription-params-with-password-required"><literal>password_required</literal></link>,
<link linkend="sql-createsubscription-params-with-run-as-owner"><literal>run_as_owner</literal></link>, and
<link linkend="sql-createsubscription-params-with-origin"><literal>origin</literal></link>.
<link linkend="sql-createsubscription-params-with-run-as-owner"><literal>run_as_owner</literal></link>,
<link linkend="sql-createsubscription-params-with-origin"><literal>origin</literal></link>, and
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>.
Only a superuser can set <literal>password_required = false</literal>.
</para>
<para>
When altering the
<link linkend="sql-createsubscription-params-with-slot-name"><literal>slot_name</literal></link>,
the <literal>failover</literal> property value of the named slot may differ from the
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
parameter specified in the subscription. When creating the slot,
ensure the slot <literal>failover</literal> property matches the
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
parameter value of the subscription. Otherwise, the slot on the
publisher may behave differently from what subscription's
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
option says. The slot on the publisher could either be
synced to the standbys even when the subscription's
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
option is disabled or could be disabled for sync
even when the subscription's
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
option is enabled.
</para>
</listitem>
</varlistentry>

23
doc/src/sgml/ref/create_subscription.sgml
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@ -117,19 +117,22 @@ CREATE SUBSCRIPTION <replaceable class="parameter">subscription_name</replaceabl
command should connect to the publisher at all. The default
is <literal>true</literal>. Setting this to
<literal>false</literal> will force the values of
<literal>create_slot</literal>, <literal>enabled</literal> and
<literal>copy_data</literal> to <literal>false</literal>.
<literal>create_slot</literal>, <literal>enabled</literal>,
<literal>copy_data</literal>, and <literal>failover</literal>
to <literal>false</literal>.
(You cannot combine setting <literal>connect</literal>
to <literal>false</literal> with
setting <literal>create_slot</literal>, <literal>enabled</literal>,
or <literal>copy_data</literal> to <literal>true</literal>.)
<literal>copy_data</literal>, or <literal>failover</literal> to
<literal>true</literal>.)
</para>
<para>
Since no connection is made when this option is
<literal>false</literal>, no tables are subscribed. To initiate
replication, you must manually create the replication slot, enable
the subscription, and refresh the subscription. See
the failover if required, enable the subscription, and refresh the
subscription. See
<xref linkend="logical-replication-subscription-examples-deferred-slot"/>
for examples.
</para>
@ -400,6 +403,18 @@ CREATE SUBSCRIPTION <replaceable class="parameter">subscription_name</replaceabl
</para>
</listitem>
</varlistentry>
<varlistentry id="sql-createsubscription-params-with-failover">
<term><literal>failover</literal> (<type>boolean</type>)</term>
<listitem>
<para>
Specifies whether the replication slots associated with the subscription
are enabled to be synced to the standbys so that logical
replication can be resumed from the new primary after failover.
The default is <literal>false</literal>.
</para>
</listitem>
</varlistentry>
</variablelist></para>
</listitem>

8
doc/src/sgml/ref/pg_dump.sgml
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@ -1588,7 +1588,13 @@ CREATE DATABASE foo WITH TEMPLATE template0;
dump can be restored without requiring network access to the remote
servers. It is then up to the user to reactivate the subscriptions in a
suitable way. If the involved hosts have changed, the connection
information might have to be changed. It might also be appropriate to
information might have to be changed. If the subscription needs to
be enabled for
<link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>,
then same needs to be done by executing
<link linkend="sql-altersubscription-params-set">
<literal>ALTER SUBSCRIPTION ... SET (failover = true)</literal></link>
after the slot has been created. It might also be appropriate to
truncate the target tables before initiating a new full table copy. If users
intend to copy initial data during refresh they must create the slot with
<literal>two_phase = false</literal>. After the initial sync, the