Re: [GENERAL] A way to let Vacuum warn if FSM settings are

I never heard any discussion on whether this should be backpatched to
8.0.X.  Should it?

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pgman wrote:
> Simon Riggs wrote:
> > On Mon, 2005-03-14 at 01:40 -0500, Tom Lane wrote:
> > > Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > > > Ron Mayer wrote:
> > > >> My reasoning why I thought the log file was more useful was
> > > >> that only an admin with access to the log files could really
> > > >> do anything about the message anyway.
> > >
> > > > The log file is useful, but I think showing the VACUUM user is _more_
> > > > useful than the log file.
> > >
> > > I think that reasoning is fundamentally unsound, because (a) a lot of
> > > people already do vacuuming via a cron job or autovacuum, and (b)
> > > autovacuum is definitely the wave of the future.  So it's foolish
> > > to design this messaging around the assumption that there will be
> > > a human attentive to the on-line output from VACUUM.  We should be
> > > ensuring that the message gets into the postmaster log --- whether
> > > it gets sent to the client is secondary.
> >
> > Personally, I prefer the postmaster log as the place for this.
> >
> > However, whilst vacuum exists as a separate command, there will be an
> > argument to return a message back to the person running it; we cannot
> > assume that people would be inattentive.
> >
> > Possibly the deciding factor should be whether autovacuum makes it fully
> > into becoming a special backend anytime soon, since in that case only
> > the log would remain as an option for reporting this message, in that
> > case.
> >
> > Can we have both?
>
> Sure.  It is very easy and in fact looks even cleaner than the original
> code because now the optional stuff is in its own function.
>
> Patch attached and applied.
>
> --
>   Bruce Momjian                        |  http://candle.pha.pa.us
>   pgman@candle.pha.pa.us               |  (610) 359-1001
>   +  If your life is a hard drive,     |  13 Roberts Road
>   +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

> Index: src/backend/storage/freespace/freespace.c
> ===================================================================
> RCS file: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v
> retrieving revision 1.38
> diff -c -c -r1.38 freespace.c
> *** src/backend/storage/freespace/freespace.c    12 Mar 2005 05:21:52 -0000    1.38
> --- src/backend/storage/freespace/freespace.c    14 Mar 2005 20:04:00 -0000
> ***************
> *** 221,226 ****
> --- 221,228 ----
>                                            * FSMHeader->relHash */
>
>
> + static void CheckFreeSpaceMapStatistics(int elevel, int numRels,
> +                         double needed);
>   static FSMRelation *lookup_fsm_rel(RelFileNode *rel);
>   static FSMRelation *create_fsm_rel(RelFileNode *rel);
>   static void delete_fsm_rel(FSMRelation *fsmrel);
> ***************
> *** 711,726 ****
>                errdetail("FSM size: %d relations + %d pages = %.0f kB shared memory.",
>                          MaxFSMRelations, MaxFSMPages,
>                          (double) FreeSpaceShmemSize() / 1024.0)));
> !
> !     if (numRels == MaxFSMRelations)
> !         ereport(NOTICE,
>               (errmsg("max_fsm_relations(%d) equals the number of relations checked",
>                MaxFSMRelations),
>                errhint("You have >= %d relations.\n"
>                         "Consider increasing the configuration parameter \"max_fsm_relations\".",
>                        numRels)));
>       else if (needed > MaxFSMPages)
> !         ereport(NOTICE,
>               (errmsg("the number of page slots needed (%.0f) exceeds max_fsm_pages (%d)",
>                needed,MaxFSMPages),
>                errhint("Consider increasing the configuration parameter \"max_fsm_relations\"\n"
> --- 713,736 ----
>                errdetail("FSM size: %d relations + %d pages = %.0f kB shared memory.",
>                          MaxFSMRelations, MaxFSMPages,
>                          (double) FreeSpaceShmemSize() / 1024.0)));
> !
> !     CheckFreeSpaceMapStatistics(NOTICE, numRels, needed);
> !     /* Print to server logs too because is deals with a config variable. */
> !     CheckFreeSpaceMapStatistics(LOG, numRels, needed);
> ! }
> !
> ! static void
> ! CheckFreeSpaceMapStatistics(int elevel, int numRels, double needed)
> ! {
> !        if (numRels == MaxFSMRelations)
> !         ereport(elevel,
>               (errmsg("max_fsm_relations(%d) equals the number of relations checked",
>                MaxFSMRelations),
>                errhint("You have >= %d relations.\n"
>                         "Consider increasing the configuration parameter \"max_fsm_relations\".",
>                        numRels)));
>       else if (needed > MaxFSMPages)
> !         ereport(elevel,
>               (errmsg("the number of page slots needed (%.0f) exceeds max_fsm_pages (%d)",
>                needed,MaxFSMPages),
>                errhint("Consider increasing the configuration parameter \"max_fsm_relations\"\n"

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073