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$Header: /cvsroot/pgsql/doc/src/sgml/ref/lock.sgml,v 1.14 1999/10/01 15:26:29 thomas Exp $

Postgres documentation

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LOCK

</refname>

<refpurpose>

Explicit lock of a table inside a transaction

Explicitly lock a table inside a transaction

</refpurpose>

</refnamediv>

<refsynopsisdiv>

<refsynopsisdivinfo>

<date>1999-07-20</date>

</refsynopsisdivinfo>

<synopsis>

LOCK [ TABLE ] <replaceable class="PARAMETER">table</replaceable>

LOCK [ TABLE ] <replaceable class="PARAMETER">table</replaceable> IN [ ROW | ACCESS ] { SHARE | EXCLUSIVE } MODE

LOCK [ TABLE ] <replaceable class="PARAMETER">table</replaceable> IN SHARE ROW EXCLUSIVE MODE

LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable>

LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN [ ROW | ACCESS ] { SHARE | EXCLUSIVE } MODE

LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EXCLUSIVE MODE

</synopsis>

<refsect2 id="R2-SQL-LOCK-1">

<variablelist>

<varlistentry>

<term><replaceable class="PARAMETER">table</replaceable></term>

<term><replaceable class="PARAMETER">name</replaceable></term>

<listitem>

<para>

The name of an existing table to lock.

<varlistentry>

<term><computeroutput>

ERROR <replaceable class="PARAMETER">table</replaceable>: Table does not exist.

ERROR <replaceable class="PARAMETER">name</replaceable>: Table does not exist.

</computeroutput></term>

<listitem>

<para>

Message returned if <replaceable class="PARAMETER">table</replaceable>

Message returned if <replaceable class="PARAMETER">name</replaceable>

does not exist.

</para>

</listitem>

table before querying. This will protect data from concurrent changes

and provide any further read operations over the table with data in their

actual current state, because SHARE lock mode conflicts with any ROW EXCLUSIVE

one acquired by writers, and your LOCK TABLE table IN SHARE MODE statement

will wait until any concurrent write operations commit or rollback.

one acquired by writers, and your

<command>LOCK TABLE <replaceable class="PARAMETER">name</replaceable> IN SHARE MODE</command>

statement will wait until any concurrent write operations commit or rollback.

<note>

<para>