From: | George Nychis <gnychis(at)cmu(dot)edu> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | performance of partitioning? |
Date: | 2007-02-27 14:00:09 |
Message-ID: | 45E43969.9080609@cmu.edu |
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Thread: | |
Lists: | pgsql-general |
Hey all,
So I have a master table called "flows" and 400 partitions in the format
"flow_*" where * is equal to some epoch.
Each partition contains ~700,000 rows and has a check such that 1 field is equal
to a value:
"flows_1107246900_interval_check" CHECK ("interval" = '2005-02-01
03:35:00'::timestamp without time zone)
Each partition has a different and unique non-overlapping check.
This query takes about 5 seconds to execute:
dp=> select count(*) from flows_1107246900;
count
--------
696836
(1 row)
This query has been running for 10 minutes now and hasn't stopped:
dp=> select count(*) from flows where interval='2005-02-01 03:35:00';
Isn't partitioning supposed to make the second query almost as fast? My WHERE
is exactly the partitioning constraint, therefore it only needs to go to 1
partition and execute the query.
Why would it take magnitudes longer to run? Am i misunderstanding something?
Thanks!
George
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