On the 'old' Red Hat AS 2.1 here is the results of explain and the query:
[ ~]$ time /usr/bin/psql mpt -c"explain select count(*) from tpv;" NOTICE: QUERY PLAN:
Aggregate (cost=4563.87..4563.87 rows=1 width=56)
-> Nested Loop (cost=870.92..4563.01 rows=342 width=56)
-> Hash Join (cost=870.92..3869.17 rows=342 width=44)
-> Seq Scan on treatment_plan (cost=0.00..956.66 rows=14844 width=28)
-> Hash (cost=602.33..602.33 rows=24033 width=16)
-> Seq Scan on treatment_plan_header (cost=0.00..602.33 rows=24033 width=16)
-> Index Scan using ada_code_pkey on ada_code (cost=0.00..2.01 rows=1 width=12)
EXPLAIN 0.010u 0.000s 0:00.03 33.3% 0+0k 0+0io 332pf+0w [~]$ time /usr/bin/psql mpt -c"select count(*) from tpv;" count ------- 33439 (1 row)
0.010u 0.000s 0:03.10 0.3% 0+0k 0+0io 332pf+0w [EMAIL PROTECTED] ~]$
On the 'new' system:
[ ~]$ /usr/bin/psql mpt -c"explain select count(*) from tpv;"
QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------
Aggregate (cost=202529.15..202529.15 rows=1 width=45)
-> Nested Loop (cost=6262.46..202496.78 rows=12948 width=45)
Join Filter: ("outer".service_code = ("inner".ada_code)::text)
-> Merge Join (cost=6262.46..6754.54 rows=12933 width=36)
Merge Cond: (("outer".appointment_order = "inner".appointment_order) AND ("outer".pat_id = "inner".pat_id))
-> Sort (cost=2335.37..2395.35 rows=23992 width=14)
Sort Key: treatment_plan_header.appointment_order, treatment_plan_header.pat_id
-> Seq Scan on treatment_plan_header (cost=0.00..589.92 rows=23992 width=14)
-> Sort (cost=3927.09..4016.27 rows=35672 width=22)
Sort Key: treatment_plan.appointment_order, treatment_plan.pat_id
-> Seq Scan on treatment_plan (cost=0.00..800.60 rows=35672 width=22)
Filter: (amount IS NULL)
-> Seq Scan on ada_code (cost=0.00..10.06 rows=406 width=9)
(13 rows)
[ ~]$
Where do I go to get clues about the results of "explain"?
Jim Apsey
Dann Corbit wrote:
I assume that the schema is identical on both systems.
After running vacuum on both systems [for each of the underlying tables in tpv], what does explain say about the queries?
Are the shared memory buffers identical on both systems?
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jimmie H. Apsey Sent: Monday, December 13, 2004 2:43 PM To: [EMAIL PROTECTED] Subject: [GENERAL] Performance differences 7.1 to 7.3
Hello all,
I have just loaded Postgresql 7.3.6-7 onto a new server on the recommendation of Tom Lane. It is part of Red Hat AS 3.
I have Postgresql 7.1.3-5 running on Red Hat AS 2.1. I have a simple view from which I select on both systems. The 7.3.6-7 version requires 18+ seconds to do a select from a particular view.
The 7.1.3-5 version requires 3+ seconds to select from the same view.
On the 7.1.3-5 version I do: [EMAIL PROTECTED] ~]$ time /usr/bin/psql mpt -c"select count(*) from tpv;" count ------- 33377 (1 row)
0.000u 0.010s 0:03.55 0.2% 0+0k 0+0io 332pf+0w [EMAIL PROTECTED] ~]$
And on 7.3.6-7 version I do: [EMAIL PROTECTED] ~]$ time /usr/bin/psql mpt -c"select count(*) from tpv;" count ------- 33377 (1 row)
0.010u 0.000s 0:18.38 0.0% 0+0k 0+0io 362pf+0w [EMAIL PROTECTED] ~]$
Does anyone have any clues as to where I should be looking for tuning/whatever?
Jim Apsey ------------------------------------------------------------------------ ----------------------------------
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