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

From: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
To: taral(at)mail(dot)utexas(dot)edu (Taral)
Cc: hackers(at)postgreSQL(dot)org
Subject: Re: [GENERAL] Long update query ? (also Re: [GENERAL] CNF vs. DNF)
Date: 1998-10-02 16:40:56
Message-ID: 199810021640.MAA10925@candle.pha.pa.us
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> > 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.

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

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