| From: | Oliver Elphick <olly(at)lfix(dot)co(dot)uk> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: How does Index Scan get used |
| Date: | 2002-02-23 00:56:01 |
| Message-ID: | 1014425762.13241.2733.camel@linda |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-sql |
On Sat, 2002-02-23 at 00:11, Tom Lane wrote:
...
> Oh BTW: the "10 rows" Oliver was wondering about are not the number of
> rows the planner thinks are in the table; they're the estimated number
> of result rows. Since there's no VACUUM ANALYZE stats available either,
> this is just a default selectivity estimate for the match clause (0.01)
> times the initial dummy reltuples value (1000). Not much content in it
> at all, eh?
Thanks, Tom. That was most informative.
--
Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C
"The LORD bless thee, and keep thee; The LORD make his
face shine upon thee, and be gracious unto thee; The
LORD lift up his countenance upon thee, and give thee
peace." Numbers 6:24-26
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