From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Bernard Frankpitt <frankpit(at)pop(dot)dn(dot)net>, pgsql-hackers <pgsql-hackers(at)postgreSQL(dot)org> |
Subject: | Re: [HACKERS] Early evaluation of constant expresions (with PATCH) |
Date: | 1999-09-22 02:17:29 |
Message-ID: | 199909220217.WAA23935@candle.pha.pa.us |
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Lists: | pgsql-hackers |
> Bernard Frankpitt <frankpit(at)pop(dot)dn(dot)net> writes:
> > The solution that I propose is to include code in the optimizer that
> > picks functions with constant arguments out of a qualification
> > clause, and evaluates them.
>
> This is something I had on my own to-do list, and I'm glad to see
> someone beat me to it. But you've only done half the job: you
> should also be folding operators with constant arguments.
>
> Also, you need to be wary of functions like now() and random().
> There probably isn't any other way to handle these than to add a
> column to pg_proc flagging functions that can't be constant-folded.
Already there, pg_proc.proiscachable.
--
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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