<para>

In synchronous replication setup, a deadlock can happen, if the transaction

has locked [user] catalog tables exclusively. This is because logical decoding of

transactions can lock catalog tables to access them. To avoid this users

must refrain from taking an exclusive lock on [user] catalog tables. This can

happen in the following ways:

has locked [user] catalog tables exclusively. See

<xref linkend="logicaldecoding-capabilities"/> for information on user

catalog tables. This is because logical decoding of transactions can lock

catalog tables to access them. To avoid this users must refrain from taking

an exclusive lock on [user] catalog tables. This can happen in the following

ways:

<itemizedlist>

<listitem>

<para>

Issuing an explicit <command>LOCK</command> on <structname>pg_class</structname>

(or any other catalog table)in a transaction.

in a transaction.

</para>

</listitem>

</para>

</listitem>

</itemizedlist>

Note that these commands that can cause deadlock apply to not only explicitly

indicated system catalog tables above but also to any other [user] catalog

table.

</para>

</sect2>

</sect1>