Re: multivariate statistics (v19)

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tatsuo Ishii <ishii(at)postgresql(dot)org>, David Steele <david(at)pgmasters(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Petr Jelinek <petr(at)2ndquadrant(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: multivariate statistics (v19)
Date: 2017-01-30 19:40:02
Message-ID: a2c4bbc5-09b3-9552-f59e-6aa93419c71a@2ndquadrant.com
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On 01/30/2017 05:55 PM, Alvaro Herrera wrote:
> Minor nitpicks:
>
> Let me suggest to use get_attnum() in CreateStatistics instead of
> SearchSysCacheAttName for each column. Also, we use type AttrNumber for
> attribute numbers rather than int16. Finally in the same function you
> have an erroneous ERRCODE_UNDEFINED_COLUMN which should be
> ERRCODE_DUPLICATE_COLUMN in the loop that searches for duplicates.
>
> May I suggest that compare_int16 be named attnum_cmp (just to be
> consistent with other qsort comparators) and look like
> return *((const AttrNumber *) a) - *((const AttrNumber *) b);
> instead of memcmp?
>

Yes, I think this is pretty much what Kyotaro-san pointed out in his
review. I'll go through the patch and make sure the correct data types
are used.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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