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how to optimize record matching?

From: Markus Wagner <wagner(at)imsd(dot)uni-mainz(dot)de>
To: pgsql-general(at)postgresql(dot)org
Subject: how to optimize record matching?
Date: 2001-10-26 07:36:52
Message-ID: 01102609365203.28855@magnus (view raw, whole thread or download thread mbox)
Lists: pgsql-general

we have a very large table (about 1 million entries), and we have an "add" 
operation that will check a new entry for equality or similarity with all of 
the existing entries. The generated SQL queries look like that:

SELECT pid FROM rec WHERE (((f_lname_PC = '2C38D2E44501ED31778E0EFDFD5200CD' 
OR f_lname_PH = 'CB85F68FFDDECD7CC39AF5BC2FBC0BBC') OR (f_lname_PC IS NULL OR 
f_lname_PH IS NULL)) AND (f_fname_PC = '3A160A9BFF2EA5A0918F5F6667A411A7' OR 
f_fname_PH = '5152F1177F0BD28FB51501597669962E') AND f_bd = 
'9E6E0D70A9B76BB6990477FCF100557E' AND f_bm = 
'4BE74390684A423853B68B9F05A4BAA0' AND f_by = 

We have set indices for each of the fields (f_*), but the matching process 
doesn't seem to become faster.
Are there any things we could improve, e. g. special index types or things 
like that?


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