| From: | Hannu Krosing <hannu(at)tm(dot)ee> |
|---|---|
| To: | Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Don Baccus <dhogaza(at)pacifier(dot)com>, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] minor bug... |
| Date: | 2000-02-10 11:41:13 |
| Message-ID: | 38A2A3D9.96879708@tm.ee |
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| Thread: | |
| Lists: | pgsql-hackers |
Thomas Lockhart wrote:
>
> > > ... there's no real reason not to support indexes on booleans, is
> > > there?
>
> afaict the only case where this would be a win is if there is a *very*
> skewed distribution of boolean values, and you *only* want the
> uncommon one. Otherwise, looking up half the rows in a table via index
> has got to be worse than just scanning the table.
One (maybe only) case I can see use for it is for a multi-field index
containing many booleans (say an index over 16 boolean fields).
------------
Hannu
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