| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Mario Splivalo <mario(dot)splivalo(at)megafon(dot)hr>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Postgres not willing to use an index? |
| Date: | 2009-02-06 18:12:19 |
| Message-ID: | 603c8f070902061012y61da659fp2d93f8ac4eece354@mail.gmail.com |
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| Lists: | pgsql-performance |
On Fri, Feb 6, 2009 at 12:41 PM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
>>>> Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> What's weird about this example is that when he sets enable_seqscan to
>> off, the bitmap index scan plan is actually substantially faster, even
>> though it in fact does scan nearly the entire heap. I don't
>> understand how it can be faster to scan the index and the heap than to
>> just scan the heap.
>
> It's cached in the second test, maybe?
I gather that the results were repeatable, but perhaps Mario could
double-check that?
...Robert
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