Bert --
You don't include some necessary details:
What version of postgres ? (8.x is noticably better at that OR / IN stuff I
think, at least to some degree)
Please include some info about your setup -- what are the settings in the
postgres config file (effective_cache_size, random_page_cost, work_mem [for
postgres 8.x) or sort_mem in 7.x)
Perhaps some info about the server in question (OS, amount of RAM, # of disks
and their setup)
Please also post the results of several EXPLAIN ANALYZE <sql here>; this will
help people see what decisions the planner is making. Perhaps best to show one
that is small, an intermdediate size and one that is painfully slow (the
explain analyze has to run the actual query in question so I realize that this
may be too slow, but some examples will help).
Greg Williamson
DBA
GlobeXplorer LLC
-----Original Message-----
From: [EMAIL PROTECTED] on behalf of Bert
Sent: Sat 4/22/2006 4:18 PM
To: pgsql-general@postgresql.org
Cc:
Subject: [GENERAL] Performance
Hi List
I have maybe an easy question but i do not find an answer, i have this
SQL query:
SELECT geom,group,production_facs FROM south_america
WHERE municipio = ''
OR municipio = 'ACRE'
OR municipio = 'ADJUNTAS'
OR municipio = 'AGUADA'
The performance of this query is quite worse as longer it gets, its
possible that this query gets over 20 to 30 OR comparisons, but then
the performance is really worse, is it possible to speed it up?
Thanks
Clemens
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TIP 2: Don't 'kill -9' the postmaster
!DSPAM:444aba30189631465223968!
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
