Re: [GENERAL] Long update query ?

Bruce Momjian <maillist@candle.pha.pa.us>

From: Bruce Momjian <maillist@candle.pha.pa.us>
To: taral@mail.utexas.edu (Taral)
Cc: daveh@insightdist.com, ser@nsu.ru, pgsql-general@postgreSQL.org
Date: 1998-10-01T22:54:19Z
Lists: pgsql-hackers, pgsql-general
[Charset iso-8859-1 unsupported, filtering to ASCII...]
> > This is caused by a semi-well known weakness in the optimizer.
> > The optimizer
> > rewrites the WHERE clause in conjunctive normal form (CNF):
> >
> >    (A and B) or (C and D) ==>  (A or C) and (A or D) and (B or C)
> > and (B or D)
> >
> 
> Wouldn't disjunctive normal form be better, since it can be implemented as
> the simple union of a set of small queries?

Please tell us more.

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