| From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Zeugswetter Andreas IZ5 <Andreas(dot)Zeugswetter(at)telecom(dot)at> |
| Cc: | pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: Selectivity of "=" (Re: [HACKERS] Index not used on simple se lect) |
| Date: | 1999-07-28 16:07:21 |
| Message-ID: | 199907281607.MAA11812@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
> Example assuming int index column:
> from to nrow_estimate
> 1 100 10005
> 101 20000 9997
> 20001 100000 10014
>
> badly scewed values (excluded in above table):
> val nrow_estimate
> 1 100000
> 5 1000000
>
> But imho this is an overkill, and seldom useful.
Yes, some commerical databases do this, though it is of questionable value.
--
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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