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help / color / mirror / Atom feedFrom: Bruce Momjian <[email protected]>
To: Marc Mamin <[email protected]>
Cc: PostgreSQL-documentation <[email protected]>
Subject: Re: [GENERAL] advisory locks: documentation hint and feature request
Date: Thu, 6 Mar 2008 13:50:36 -0500 (EST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <CA896D7906BF224F8A6D74A1B7E54AB301750D0E@JENMAIL01.ad.intershop.net>
Marc Mamin wrote:
> doing this, I missed an information in the documentation that would be
> useful to add:
>
>
> pg_locks columns definition
> ---------------------------
>
> current definition:
>
> objid : OID of the object within its system catalog,
> or NULL if the object is not a general database object
>
> to add: "For advisory locks it is used to distinguish the two key
> spaces (one int8 or two int4 keys)
>
>
> Table 9-56. Advisory Lock Functions (8.3 Beta)
> -----------------------------------
> current: (note that these two key spaces do not overlap)
>
> to add: "; The two key spaces are separated on the column objid in the
> pg_locks view"
>
I have added your suggested changes to the docs with the attached patch.
Thanks.
> Moreover I missed some function that would allow a cleaner
> implementation of my features
> (reducing the need to query the pg_locks view)
>
> For example:
>
> --current shared lock count (owned / all)
> pg_advisory_lock_shared_count_my(key bigint)
> pg_advisory_lock_shared_count_all(key bigint)
>
>
> --enforce exclusive locks so that they cannot be stacked
> pg_try_advisory_lock_single(key bigint)
Sorry, I am afraid they would not have general-enough usefulness.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Attachments:
[text/x-diff] /rtmp/diff (2.3K, 2-%2Frtmp%2Fdiff)
download | inline diff:
Index: doc/src/sgml/catalogs.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/catalogs.sgml,v
retrieving revision 2.161
diff -c -c -r2.161 catalogs.sgml
*** doc/src/sgml/catalogs.sgml 31 Jan 2008 18:40:02 -0000 2.161
--- doc/src/sgml/catalogs.sgml 6 Mar 2008 18:48:54 -0000
***************
*** 5691,5697 ****
<entry>any OID column</entry>
<entry>
OID of the object within its system catalog, or NULL if the
! object is not a general database object
</entry>
</row>
<row>
--- 5691,5700 ----
<entry>any OID column</entry>
<entry>
OID of the object within its system catalog, or NULL if the
! object is not a general database object.
! For advisory locks it is used to distinguish the two key
! spaces (<literal>1</> for an int8 key, <literal>2</> for two
! int4 keys).
</entry>
</row>
<row>
Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/func.sgml,v
retrieving revision 1.422
diff -c -c -r1.422 func.sgml
*** doc/src/sgml/func.sgml 3 Mar 2008 18:09:02 -0000 1.422
--- doc/src/sgml/func.sgml 6 Mar 2008 18:48:58 -0000
***************
*** 12378,12384 ****
<para>
<function>pg_advisory_lock</> locks an application-defined resource,
which can be identified either by a single 64-bit key value or two
! 32-bit key values (note that these two key spaces do not overlap). If
another session already holds a lock on the same resource, the
function will wait until the resource becomes available. The lock
is exclusive. Multiple lock requests stack, so that if the same resource
--- 12378,12385 ----
<para>
<function>pg_advisory_lock</> locks an application-defined resource,
which can be identified either by a single 64-bit key value or two
! 32-bit key values (note that these two key spaces do not overlap).
! The key type is specified in <literal>pg_locks.objid</>. If
another session already holds a lock on the same resource, the
function will wait until the resource becomes available. The lock
is exclusive. Multiple lock requests stack, so that if the same resource
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