Re: [HACKERS] PoC: full merge join on comparison clause

From: Alexander Kuzmenkov <a(dot)kuzmenkov(at)postgrespro(dot)ru>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Jeff Davis <pgsql(at)j-davis(dot)com>
Subject: Re: [HACKERS] PoC: full merge join on comparison clause
Date: 2018-11-21 13:02:47
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On 11/19/18 04:46, Tom Lane wrote:
> In short, proceeding like the above when we can't find another plan
> type for a full join seems like it fixes a far wider variety of cases.
> The possibility that maybe we could do some of those cases a bit faster
> isn't sufficiently attractive to me to justify also putting in a
> mechanism like this patch proposes. We only rarely see complaints at
> all about can't-do-a-full-join problems, and I do not think this patch
> would fix enough of those complaints to be worthwhile.

I agree, the automated UNION substitutions seems to be a better
approach. I'll mark this patch as rejected then.

Alexander Kuzmenkov
Postgres Professional:
The Russian Postgres Company

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