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List:       pgsql-performance
Subject:    Re: [PERFORM] Database design - best practice
From:       Bèrto ëd Sèra <berto.d.sera () gmail ! com>
Date:       2012-11-28 13:29:47
Message-ID: CAKwGa__-oh_J6zr0jYGQ0GqeiCL_OkFq83Judd0rXE92wa7NnQ () mail ! gmail ! com
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Hi Kristian,

> " I can't see why it would make sense to put that into a separate table and
> join in the values "
> You don't normalize for performance. People DEnormalize for performance.

Yes. In short, you seem more of a developer than a RDBMS guy. This is
not a personal fault, but it's a *very* dangerous state to be in and
you should address the problem asap. Erase from your head all you
could possibly know in terms of "putting it into a file" and read very
basic texts about normal forms. Like this:

http://en.wikipedia.org/wiki/Database_normalization

As already said by Willem, learn to test your stuff. There is a
\timing command in psql, use it.

For example (addressing your other post), you want to check how long it takes to
UPDATE "adverts"
SET
  "last_observed_at" = '2012-11-28 00:02:30.265154',
  "data_source_id" ='83d024a57bc2958940f3ca281bddcbf4'
WHERE
  "adverts"."id" IN ( 1602382, 4916432, ...... 3637777 ) ;

as opposed to

UPDATE "adverts"
SET
  "last_observed_at" = '2012-11-28 00:02:30.265154',
  "data_source_id" ='83d024a57bc2958940f3ca281bddcbf4'
WHERE
  "adverts"."id" = 1602382 OR
  "adverts"."id" = 4916432 OR
   ......
  "adverts"."id" = 3637777;

My 5 pence
Bèrto
-- 
==============================
If Pac-Man had affected us as kids, we'd all be running around in a
darkened room munching pills and listening to repetitive music.


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