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. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026