Re: current_query in pg_stat_activity

Attached patch applied.  Thanks for the analysis.

---------------------------------------------------------------------------

Jan Wieck wrote:
> Tom Lane wrote:
> > Oliver Fromme <olli@lurza.secnetix.de> writes:
> >> Tom Lane wrote:
> >>>> Oliver Fromme <olli@lurza.secnetix.de> writes:
> >>>>> The "current_query" column in the "pg_stat_activity" system
> >>>>> table seems to be limited to 255 characters.  Is there a way
> >>>>> to increase that limit, in order to see queries completely
> >>>>> which are longer than 255 characters?
> >>>>
> >>>> You could fool with PGSTAT_ACTIVITY_SIZE in pgstat.h, but you probably
> >>>> need to keep it under 1000 --- note the comments associated with
> >>>> PGSTAT_NUM_TABENTRIES.
> >
> >> Thanks!  It appears that the size is ultimately limited
> >> by the MTU of the localhost interface, which is 16K on
> >> my platform (FreeBSD), so I should be able to increase
> >> PGSTAT_ACTIVITY_SIZE to something like 15K, right?
> >
> > You'll probably find the overhead of the stats collector ballooning
> > quite a lot if you increase the max message size by a factor of 15 :-(.
> > But give it a try.
> >
> >> Oh, by the way, while I'm at it, I think I found a small
> >> bug in the second of those formulas (PostgreSQL 7.3.5):
> >
> >> #define PGSTAT_NUM_TABPURGE   ((1000 - sizeof(PgStat_MsgHdr))   \
> >>                               / sizeof(PgStat_TableEntry))
> >
> >> That should be sizeof(Oid), shouldn't it?  The bug doesn't
> >> hurt because a Oid is much smaller than a PgStat_TableEntry,
> >> but it limits the number of them inside a PgStat_MsgTabpurge
> >> much more than necessary.
> >
> > I think you are right.  Jan?
>
> Looks very much like, as the payload of the purge message is just an
> array of oids.
>
>
> Jan
>
> --
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--
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Index: src/include/pgstat.h
===================================================================
RCS file: /cvsroot/pgsql-server/src/include/pgstat.h,v
retrieving revision 1.18
diff -c -c -r1.18 pgstat.h
*** src/include/pgstat.h    25 Dec 2003 03:52:51 -0000    1.18
--- src/include/pgstat.h    2 Mar 2004 16:34:25 -0000
***************
*** 271,277 ****
   * ----------
   */
  #define PGSTAT_NUM_TABPURGE        ((1000 - sizeof(PgStat_MsgHdr))            \
!                                 / sizeof(PgStat_TableEntry))

  /* ----------
   * PgStat_MsgTabpurge            Sent by the backend to tell the collector
--- 271,277 ----
   * ----------
   */
  #define PGSTAT_NUM_TABPURGE        ((1000 - sizeof(PgStat_MsgHdr))            \
!                                 / sizeof(Oid))

  /* ----------
   * PgStat_MsgTabpurge            Sent by the backend to tell the collector