Re: [HACKERS] RE: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF) - Mailing list pgsql-hackers

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> > Another idea is that we rewrite queries such as:
> >
> >     SELECT *
> >     FROM tab
> >     WHERE (a=1 AND b=2 AND c=3) OR
> >           (a=1 AND b=2 AND c=4) OR
> >           (a=1 AND b=2 AND c=5) OR
> >           (a=1 AND b=2 AND c=6)
> >
> > into:
> >
> >     SELECT *
> >     FROM tab
> >     WHERE (a=1 AND b=2) AND (c=3 OR c=4 OR c=5 OR c=6)
>
> Very nice, but that's like trying to code factorization of numbers... not
> pretty, and very CPU intensive on complex queries...

Yes, but how large are the WHERE clauses going to be?  Considering the
cost of cnfify() and UNION, it seems like a clear win.  Is it general
enough to solve our problems?

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