| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
| Cc: | Fredrik Olsson <fredrik(dot)olsson(at)treyst(dot)se>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Inherited indexes. |
| Date: | 2005-10-04 15:05:49 |
| Message-ID: | 8354.1128438349@sss.pgh.pa.us |
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"Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:
> On Sun, Oct 02, 2005 at 09:46:07PM -0400, Tom Lane wrote:
>> 1. A cross-table index would need to store a table OID as well as the
>> existing block/offset information in order to tell you what an entry is
>> pointing at.
> Wouldn't it make more sense to use a smaller pointer to a table of OIDs
> that that index covers?
Smaller than what? Don't tell me you want to restrict how many tables a
cross-table index can handle :-(
In any case, the gain from doing that would be exactly zero because of
alignment considerations: the size of an index tuple header really has
to be a multiple of MAXALIGN.
regards, tom lane
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