Re: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)

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

From: Bruce Momjian <maillist@candle.pha.pa.us>
To: taral@mail.utexas.edu (Taral)
Cc: hackers@postgreSQL.org
Date: 1998-10-02T16:40:56Z
Lists: pgsql-hackers, pgsql-general
[Charset iso-8859-1 unsupported, filtering to ASCII...]
> > This is interesting.  Check CNF size and DNF size.  Choose smallest. 
> > CNF uses existing code, DNF converts to UNIONs.  How do you return the
> > proper rows with/without proper duplicates?
> 
> Create a temporary oid hash? (for each table selected on, I guess)
> 
> Taral
> 

What I did with indexes was to run the previous OR clause index
restrictions through the qualification code, and make sure it failed,
but I am not sure how that is going to work with a more complex WHERE
clause.  Perhaps I need to restrict this to just simple cases of
constants, which are easy to pick out an run through.  Doing this with
joins would be very hard, I think.

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