From: Milen Kulev <makulev@gmx.net>
To: 'Tom Lane' <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Partition elimination problem
Date: Mon, 18 Sep 2006 08:07:51 +0200
Message-ID: <000001c6dae8$cc658170$0a00a8c0@trivadis.com> (raw)
In-Reply-To: <27954.1158534812@sss.pgh.pa.us>
Hi Tom,
You are right, of course :
pgpool=# set constraint_exclusion = on ;
SET
pgpool=# explain analyze select * from part where id1=3 and id2=5 ;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------
-----------------------------
Result (cost=0.00..289.92 rows=3 width=130) (actual time=3.604..27.839 rows=483 loops=1)
-> Append (cost=0.00..289.92 rows=3 width=130) (actual time=3.600..22.550 rows=483 loops=1)
-> Seq Scan on part (cost=0.00..24.85 rows=1 width=130) (actual time=0.001..0.001 rows=0 loops=1)
Filter: ((id1 = 3) AND (id2 = 5))
-> Bitmap Heap Scan on part_id1_0_10 part (cost=1.02..9.50 rows=1 width=130) (actual time=0.014..0.014 rows=0
loops=1)
Recheck Cond: (id1 = 3)
Filter: (id2 = 5)
-> Bitmap Index Scan on idx_part_id1_0_10 (cost=0.00..1.02 rows=5 width=0) (actual time=0.009..0.009
rows=0 loops=1)
Index Cond: (id1 = 3)
-> Bitmap Heap Scan on part_id1_0_10__id2_0_10 part (cost=2.52..255.56 rows=1 width=130) (actual
time=3.578..20.377 rows=483 loops=1)
Recheck Cond: (id2 = 5)
Filter: (id1 = 3)
-> Bitmap Index Scan on idx_part_id1_0_10__id2_0_10 (cost=0.00..2.52 rows=148 width=0) (actual
time=3.460..3.460 rows=5242 loops=1)
Index Cond: (id2 = 5)
Total runtime: 30.576 ms
Now the execution plan looks good.
And now I have another problem -> constraint_exclusion is on in the postgresql.conf file.
BUT in my psql session I see something different ;(. Only after setting this parameter explicitely in the session, it
works.
What I have done wrong ?
pgpool=# show constraint_exclusion ;
constraint_exclusion
----------------------
off
(1 row)
pgpool=# set constraint_exclusion = on ;
SET
pgpool=# show constraint_exclusion ;
constraint_exclusion
----------------------
on
(1 row)
Best Regards.
Milen
-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Monday, September 18, 2006 1:14 AM
To: Milen Kulev
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Partition elimination problem
"Milen Kulev" <makulev@gmx.net> writes:
> My Problem is that I don't see partiotion elimination feature
> (Parameer = constraint_exclusion is ON):
Your example works as expected for me. You *sure* you have constraint_exclusion turned on?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: makulev@gmx.net, tgl@sss.pgh.pa.us
Subject: Re: Partition elimination problem
In-Reply-To: <000001c6dae8$cc658170$0a00a8c0@trivadis.com>
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