| From: | "Jie Zhang" <jzhang(at)greenplum(dot)com> |
|---|---|
| To: | "Gavin Sherry" <swm(at)linuxworld(dot)com(dot)au>, "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
| Cc: | "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Bitmap index thoughts |
| Date: | 2006-12-28 17:00:30 |
| Message-ID: | C1B9382E.C7E9%jzhang@greenplum.com |
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| Lists: | pgsql-hackers |
On 12/27/06 3:16 AM, "Gavin Sherry" <swm(at)linuxworld(dot)com(dot)au> wrote:
> On Wed, 27 Dec 2006, Heikki Linnakangas wrote:
>
>> Jie Zhang wrote:
>>> The "bitmap data segment" sounds good in terms of space. The problem is that
>>> one bitmap is likely to occupy more pages than before, which may hurt the
>>> query performance.
>>
>> We could have segments of say 1/5 of page. When a bitmap grows larger
>> than that, the bitmap would be moved to a page of its own. That way we
>> wouldn't get unnecessary fragmentation with large bitmaps, but small
>> bitmaps would be stored efficiently.
>
> Yes.
I see. This sounds good. I will think more about this.
Thanks,
Jie
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