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Re: Small fix for inv_getsize

From: Denis Perchine <dyp(at)perchine(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Small fix for inv_getsize
Date: 2000-11-02 17:02:23
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-patches
> > Just realized that inv_getsize is a little bit wrong :-)). It just get
> > the first page, not last
> > Here is the patch which will fix the behavior.
> No it doesn't; it's a loop, and your patch will change nothing.  Your
> original version tried to stop after fetching one tuple, which was
> wrong because of visibility considerations.
> Now that I think about it, this code could do a two-key scan backwards
> and stop after finding the first (last) valid tuple, but that's more
> than a one-line change.

Actual logic is to find the maximum of pageno, for specified oid.
I do index scan on 2-keys index, specifying only one key as constraint...
If I do index scan forward I will get the smallest pageno first...
Otherwise I get the highest pageno... And this is what I want...
Or I get something wrong? Isn't this how order by on index is done?

Sincerely Yours,
Denis Perchine

E-Mail: dyp(at)perchine(dot)com
FidoNet: 2:5000/120.5

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