Re: [HACKERS] nested loops in joins, ambiguous rewrite rules - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] nested loops in joins, ambiguous rewrite rules
Date
Msg-id 199901311935.OAA07665@candle.pha.pa.us
Whole thread Raw
In response to Re: [HACKERS] nested loops in joins, ambiguous rewrite rules  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> Perhaps if we develop a slightly more complex measure to compare against
> the GEQO threshold, we can do better in deciding when to kick in GEQO.
> A brain-dead suggestion is number of tables + number of indexes ...
> does anyone know whether that is a good measure of the number of cases
> considered in the optimizer?

That is an excellent suggestion.  We have always seen 6-table joins that
are short with geqo, and some longer.  Perhaps that is the cause.

--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026
 


pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: [HACKERS] nested loops in joins, ambiguous rewrite rules
Next
From: The Hermit Hacker
Date:
Subject: Re: Problems with anon CVS?