| From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | tgl(at)sss(dot)pgh(dot)pa(dot)us (Tom Lane) |
| Cc: | charlie(at)k4azl(dot)net, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] nested loops in joins, ambiguous rewrite rules |
| Date: | 1999-01-31 19:35:31 |
| Message-ID: | 199901311935.OAA07665@candle.pha.pa.us |
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| Thread: | |
| Lists: | 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(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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