From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: record identical operator |
Date: | 2013-09-14 13:09:48 |
Message-ID: | 20130914130948.GF7437@awork2.anarazel.de |
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Thread: | |
Lists: | pgsql-hackers |
On 2013-09-13 19:20:11 -0700, Kevin Grittner wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>
> > Not one that's dependendant on padding bytes, null bitmaps that
> > can or cannot be present and such.
>
> Can you provide an example of where that's an issue with this
> patch?
I haven't yet tested your patch, but what I am talking about is that
e.g.: SELECT (ARRAY[1,2,3,NULL])[1:3] = ARRAY[1,2,3];
obviously should be true. But both arrays don't have the same binary
representation since the former has a null bitmap, the latter not.
So, if you had a composite type like (int4[]) and would compare that
without invoking operators you'd return something false in some cases
because of the null bitmaps.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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