| From: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
|---|---|
| To: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> |
| Cc: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Andres Freund <andres(at)anarazel(dot)de>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Mark Dilger <hornschnorter(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] PATCH: multivariate histograms and MCV lists |
| Date: | 2019-03-13 06:37:45 |
| Message-ID: | CAKJS1f_6qDQj9m2H0jF4bRkZVLpfc7O9E+MxdXrq0wgv0z1NrQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, 13 Mar 2019 at 17:20, Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> bms_member_index seems working differently than maybe expected.
>
> bms_member_index((2, 4), 0) => 0, (I think) should be -1
> bms_member_index((2, 4), 1) => 0, should be -1
> bms_member_index((2, 4), 2) => 0, should be 0
> bms_member_index((2, 4), 3) => 1, should be -1
> bms_member_index((2, 4), 4) => 1, should be 1
> bms_member_index((2, 4), 5) => 2, should be -1
> bms_member_index((2, 4), 6) => 2, should be -1
> ...
> bms_member_index((2, 4), 63) => 2, should be -1
> bms_member_index((2, 4), 64) => -1, correct
>
> It works correctly only when x is a member - the way the function
> is maybe actually used in this patch -, or needs to change the
> specifiction (or the comment) of the function.
Looks like:
+ if (wordnum >= a->nwords)
+ return -1;
should be:
+ if (wordnum >= a->nwords ||
+ (a->word[wordnum] & ((bitmapword) 1 << bitnum)) == 0)
+ return -1;
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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