From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Shaun Thomas <sthomas(at)townnews(dot)com> |
Cc: | pgsql-admin(at)postgresql(dot)org |
Subject: | Re: Cost limit. |
Date: | 2001-05-18 16:12:07 |
Message-ID: | 200105181612.f4IGC7U29140@candle.pha.pa.us |
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Lists: | pgsql-admin |
> Actually I was thinking of something to cut the query off at the pass. I
> looked through the code, and it does a query plan and uses the one with
> least cost. So, theoretically, I should be able to hack the code so that
> it will refuse to execute a query if the best query plan has an estimated
> cost of over 100,000 for example.
>
> Some kind of error like: "Query not executed due to detection of possible
> cross product."
>
> Of course, I'd like to stay away from source hacks, besides It would be
> nice to tune from postgresql.conf as a parameter like max_query_cost.
>
> The source is a bit spaghetti-ish, and I'm having a hard time following
> some of the macros, typedefs and structs. I don't think I could add
> a feature like this myself.
I don't think our optimizer estimates are that accurate.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
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