performance and number of selected columns

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От Dirk Lutzebaeck
Тема performance and number of selected columns
Дата
Msg-id 14633.20816.626234.631719@ampato.core.aeccom.com
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Ответы Re: performance and number of selected columns  (Dirk Lutzebaeck <lutzeb@aeccom.com>)
Re: performance and number of selected columns  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
Hi,

say I have three tables a,b,c with lots of columns (say 10 for each
table). Using psql command line, why does

 SELECT a.*,b.*,c.* FROM a,b,c

takes much more longer (in my specifc case 3 times) than only
selecting one column like

 SELECT a.oid, b.oid, c.oid FROM a,b,c.

This is on 7.0. Can I play with buffer sizes? Indexes exist on most
of the columns. Columns in the second line can be arbitrary.

Dirk



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