Re: Table size growing for no reason

The table is vacuumed all the time.
Pg_autovacuum runs.

I started thinking - what did I change right before this happened?

I was playing around trying to tweak the performance of the database.
As part of the process, I increased the number of WAL buffers to 32 and
the checkpoint segments to 16.
That appears to have been the culprit! I set them back at the same
levels I was previously using (16 and 4, respectively), and now the
table is no longer misbehaving.

That was quite interesting - can someone in the core team verify that
too high a number for these 2 parameters could have caused this
behavior?

Thanks in advance.

Benjamin

> -----Original Message-----
> From: pgsql-admin-owner(at)postgresql(dot)org
> [mailto:pgsql-admin-owner(at)postgresql(dot)org] On Behalf Of Rodrigo De Leon
> Sent: Thursday, July 13, 2006 7:08 PM
> To: pgsql-admin(at)postgresql(dot)org
> Subject: Re: [ADMIN] Table size growing for no reason
>
> On 7/13/06, Benjamin Krajmalnik <kraj(at)illumen(dot)com> wrote:
> >
> >
> > I am running PostgreSQL 8.1.4 on windows.
> > I have a table with the following structure:
> >
> > CREATE TABLE "public"."tblksaura" (
> > "ksaurasysid" SERIAL,
> > "testtime" TIMESTAMP WITHOUT TIME ZONE,
> > "lasthouralive" DOUBLE PRECISION[],
> > "last24hrsalive" DOUBLE PRECISION[],
> > "last7daysalive" DOUBLE PRECISION[],
> > "last30daysalive" DOUBLE PRECISION[],
> > "sumalivelasthour" DOUBLE PRECISION,
> > "sumreplylasthour" DOUBLE PRECISION,
> > "sumalivelast24hrs" DOUBLE PRECISION,
> > "sumalivelast7days" DOUBLE PRECISION,
> > "sumalivelast30days" DOUBLE PRECISION,
> > "sumreplylast24hrs" DOUBLE PRECISION,
> > "sumreplylast7days" DOUBLE PRECISION,
> > "sumreplylast30days" DOUBLE PRECISION,
> > "lasthourreply" DOUBLE PRECISION[],
> > "last24hrsreply" DOUBLE PRECISION[],
> > "last7daysreply" DOUBLE PRECISION[],
> > "last30daysreply" DOUBLE PRECISION[],
> > "lasthourstatus" INTEGER[],
> > "totaltestslasthour" BIGINT[],
> > "totaltestslast24hrs" BIGINT[],
> > "totaltestslast7days" BIGINT[],
> > "totaltestslast30days" BIGINT[],
> > "kstestssysid" INTEGER,
> > CONSTRAINT "tblksaura_kstestssysid_key" UNIQUE("kstestssysid"),
> > CONSTRAINT "tblksaura_pkey" PRIMARY KEY("ksaurasysid"),
> > CONSTRAINT "tblksaura_fk_tblkstests" FOREIGN KEY ("kstestssysid")
> > REFERENCES "public"."tblkstests"("kstestssysid")
> > MATCH FULL
> > ON DELETE CASCADE
> > ON UPDATE NO ACTION
> > NOT DEFERRABLE
> > ) WITHOUT OIDS;
> >
> > CREATE UNIQUE INDEX "tblksaura_idx_kstestssysid" ON
> "public"."tblksaura"
> > USING btree ("kstestssysid", "testtime");
> >
> > Running explain select * from tblkaura indicates that the
> width of the
> > row is 1859.
> > The table has 3297 rows.
> >
> > Initially, it was 6.8MB. All of a sudden it has started growing in
> > size - both on the main table size, the indices, and toast.
> >
> > I truncated the table and reloaded the data - it went back
> to 6.8 Mb.
> >
> > This table is updated at a rate of about 10-12 updates
> statements per
> > second, by a single connection (a monitoring agent).
> >
> > What can be causing this strange behavior? Is there anything which
> > can be done? The update is being performed by a pl/pgsql
> stored procedure.
> >
> > The SQL query which is updating it uses the primary key for
> > retrieveing the field.
> >
> > The query looks as follows:
> >
> > update tblksaura
> > set
> > testtime = t_mytesttime,
> > totaltestslasthour = ia_totaltestslasthour,
> > totaltestslast24hrs = ia_totaltestslast24hrs,
> > totaltestslast7days = ia_totaltestslast7days,
> > totaltestslast30days = ia_totaltestslast30days,
> > lasthourstatus = ia_lasthourstatus,
> > lasthourreply = fa_lasthourreply,
> > last24hrsreply = fa_last24hrsreply,
> > last7daysreply = fa_last7daysreply,
> > last30daysreply = fa_last30daysreply,
> > lasthouralive = fa_lasthouralive,
> > last24hrsalive = fa_last24hrsalive,
> > last7daysalive = fa_last7daysalive,
> > last30daysalive = fa_last30daysalive,
> > sumalivelasthour = r_aurarecord.sumalivelasthour,
> > sumreplylasthour = r_aurarecord.sumreplylasthour,
> > sumalivelast24hrs = r_aurarecord.sumalivelast24hrs,
> > sumreplylast24hrs = r_aurarecord.sumreplylast24hrs,
> > sumalivelast7days = r_aurarecord.sumalivelast7days,
> > sumreplylast7days = r_aurarecord.sumreplylast7days,
> > sumalivelast30days =
> > r_aurarecord.sumalivelast30days,
> > sumreplylast30days = r_aurarecord.sumreplylast30days
> > where ksaurasysid = r_aurarecord.ksaurasysid;
> >
> >
> > Any assistance in getting this tracked down will be deeply
> appreciated.
> >
> > Looking at the current running processes in pgadmin I cannot see
> > anything which could be causing this.
> >
> > After about 1 hour of running, the table is now over 450MB!!!!!
> >
> > I am out of ideas.
>
> VACUUM?
>
> http://www.postgresql.org/docs/8.1/static/maintenance.html#ROU
> TINE-VACUUMING
>
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