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Accept relations of any kind in LOCK TABLE

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The restriction that only tables and views can be locked by LOCK TABLE
is quite arbitrary, since the underlying mechanism can lock any relation
type.  Drop the restriction so that programs such as pg_dump can lock
all relations they're interested in, preventing schema changes that
could cause a dump to fail after expending much effort.

Backpatch to 9.5.

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reported-by: Wells Oliver <wells.oliver@gmail.com>
Discussion: https://postgr.es/m/20201021200659.GA32358@alvherre.pgsql
This commit is contained in:
Alvaro Herrera
2020-10-27 13:49:19 -03:00
parent 2339038a9b
commit 2f0baa244f
4 changed files with 40 additions and 21 deletions
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21
doc/src/sgml/ref/lock.sgml
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@ -16,7 +16,7 @@ PostgreSQL documentation
<refnamediv>
<refname>LOCK</refname>
<refpurpose>lock a table</refpurpose>
<refpurpose>lock a named relation (table, etc)</refpurpose>
</refnamediv>
<refsynopsisdiv>
@ -34,7 +34,9 @@ LOCK [ TABLE ] [ ONLY ] <replaceable class="PARAMETER">name</replaceable> [ * ]
<title>Description</title>
<para>
<command>LOCK TABLE</command> obtains a table-level lock, waiting
<command>LOCK TABLE</command> obtains a table-level lock on a
relation (table, partitioned table, foreign table, view,
materialized view, index, composite type, sequence), waiting
if necessary for any conflicting locks to be released. If
<literal>NOWAIT</literal> is specified, <command>LOCK
TABLE</command> does not wait to acquire the desired lock: if it
@ -110,17 +112,18 @@ LOCK [ TABLE ] [ ONLY ] <replaceable class="PARAMETER">name</replaceable> [ * ]
<term><replaceable class="PARAMETER">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing table to
lock. If <literal>ONLY</> is specified before the table name, only that
table is locked. If <literal>ONLY</> is not specified, the table and all
its descendant tables (if any) are locked. Optionally, <literal>*</>
The name (optionally schema-qualified) of an existing relation to
lock. If <literal>ONLY</literal> is specified before a table name, only that
table is locked. If <literal>ONLY</literal> is not specified, the table and all
its descendant tables (if any) are locked. Optionally, <literal>*</literal>
can be specified after the table name to explicitly indicate that
descendant tables are included.
descendant tables are included. When locking a view, all relations appearing
in the view definition are locked, regardless of <literal>ONLY</literal>.
</para>
<para>
The command <literal>LOCK TABLE a, b;</> is equivalent to
<literal>LOCK TABLE a; LOCK TABLE b;</>. The tables are locked
The command <literal>LOCK TABLE a, b;</literal> is equivalent to
<literal>LOCK TABLE a; LOCK TABLE b;</literal>. The relations are locked
one-by-one in the order specified in the <command>LOCK
TABLE</command> command.
</para>