Re: Partition elimination problem

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(at)sss(dot)pgh(dot)pa(dot)us]
Sent: Monday, September 18, 2006 1:14 AM
To: Milen Kulev
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] Partition elimination problem

"Milen Kulev" <makulev(at)gmx(dot)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