Message-ID: <541C18C5.3080204@gmx.de>
Date: Fri, 19 Sep 2014 13:51:33 +0200
From: =?ISO-8859-15?Q?Bj=F6rn_Wittich?= <Bjoern_Wittich@gmx.de>
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To: pgsql-performance@postgresql.org
Subject: query a table with lots of coulmns
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Hi mailing list,

I am relatively new to postgres. I have a table with 500 coulmns and 
about 40 mio rows. I call this cache table where one column is a unique 
key (indexed) and the 499 columns (type integer) are some values 
belonging to this key.

Now I have a second (temporary) table (only 2 columns one is the key of 
my cache table) and I want  do an inner join between my temporary table 
and the large cache table and export all matching rows. I found out, 
that the performance increases when I limit the join to lots of small parts.
But it seems that the databases needs a lot of disk io to gather all 499 
data columns.
Is there a possibilty to tell the databases that all these colums are 
always treated as tuples and I always want to get the whole row? Perhaps 
the disk oraganization could then be optimized?


Thank you for feedback and ideas
Best
Neo


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