Date: Thu, 30 Aug 2012 16:56:38 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-docs@postgreSQL.org
Subject: Re: Comment on max_locks_per_transaction
Message-ID: <20120830205638.GA8753@momjian.us>
References: <4FDB796A.7080803@agliodbs.com>
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I have applied the attached patch to document this issue.

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On Fri, Jun 15, 2012 at 11:05:30AM -0700, Josh Berkus wrote:
> Folks,
> 
> Way it is now:
> 
> ===============
> 
> max_locks_per_transaction (integer)
> 
>     The shared lock table tracks locks on max_locks_per_transaction *
> (max_connections + max_prepared_transactions) objects (e.g., tables);
> hence, no more than this many distinct objects can be locked at any one
> time. This parameter controls the average number of object locks
> allocated for each transaction; individual transactions can lock more
> objects as long as the locks of all transactions fit in the lock table.
> This is not the number of rows that can be locked; that value is
> unlimited. The default, 64, has historically proven sufficient, but you
> might need to raise this value if you have clients that touch many
> different tables in a single transaction. This parameter can only be set
> at server start.
> 
>     Increasing this parameter might cause PostgreSQL to request more
> System V shared memory than your operating system's default
> configuration allows. See Section 17.4.1 for information on how to
> adjust those parameters, if necessary.
> 
>     When running a standby server, you must set this parameter to the
> same or higher value than on the master server. Otherwise, queries will
> not be allowed in the standby server.
> 
> ================
> 
> The way it should be:
> 
> max_locks_per_transaction (integer)
> 
>     The shared lock table tracks locks on max_locks_per_transaction *
> (max_connections + max_prepared_transactions) objects (e.g., tables);
> hence, no more than this many distinct objects can be locked at any one
> time. This parameter controls the average number of object locks
> allocated for each transaction; individual transactions can lock more
> objects as long as the locks of all transactions fit in the lock table.
> This is not the number of rows that can be locked; that value is
> unlimited. This parameter can only be set at server start.
> 
> The default, 64, has historically proven sufficient for most databases,
> but you might need to raise this value if you have clients that touch
> many different tables in a single transaction.  Databases with several
> tables with many partitions each can require raising this setting.  The
> PostgreSQL activity log will contain a fairly clear error message
> suggesting raising max_locks_per_transaction if needed.
> 
>     Increasing this parameter might cause PostgreSQL to request more
> System V shared memory than your operating system's default
> configuration allows. See Section 17.4.1 for information on how to
> adjust those parameters, if necessary.
> 
>     When running a standby server, you must set this parameter to the
> same or higher value than on the master server. Otherwise, queries will
> not be allowed in the standby server.
> 
> 
> -- 
> Josh Berkus
> PostgreSQL Experts Inc.
> http://pgexperts.com
> 
> -- 
> Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-docs

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

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diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index d5fa94e..ade9f79
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** dynamic_library_path = 'C:\tools\postgre
*** 5550,5558 ****
          fit in the lock table.  This is <emphasis>not</> the number of
          rows that can be locked; that value is unlimited.  The default,
          64, has historically proven sufficient, but you might need to
!         raise this value if you have clients that touch many different
!         tables in a single transaction. This parameter can only be set at
!         server start.
         </para>
  
         <para>
--- 5550,5558 ----
          fit in the lock table.  This is <emphasis>not</> the number of
          rows that can be locked; that value is unlimited.  The default,
          64, has historically proven sufficient, but you might need to
!         raise this value if you have queries that touch many different
!         tables in a single transaction, e.g. query of a parent table with
!         many children.  This parameter can only be set at server start.
         </para>
  
         <para>

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