Re: [GENERAL] advisory locks: documentation hint and feature request - Mailing list pgsql-docs

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  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://postgres.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
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