| From: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: GiST buffering build, bug in levelStep calculation |
| Date: | 2012-05-31 10:34:51 |
| Message-ID: | CAPpHfdvnUuuQoze9NZt6AnThaJiP2a770HO5EozaPH=n3ZGbzQ@mail.gmail.com |
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On Thu, May 31, 2012 at 1:36 PM, Heikki Linnakangas <
heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> I note that the calculations assume that leaf tuples and internal tuples
> have similar sizes. We calculate the average leaf tuple size, and use that
> to calculate the fan-out of internal pages. On some GiST opclasses, the
> values stored on internal pages might be quite different from the leaf
> tuples. I don't think we need to worry about that in practice, these
> calculations are not very accurate anyway, but perhaps a comment would be
> in order.
>
Probably we could collect per-level statistics of average tuple size?
------
With best regards,
Alexander Korotkov.
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