Re: Proposal : Parallel Merge Join

From: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal : Parallel Merge Join
Date: 2017-03-07 16:38:51
Message-ID: CAFiTN-tzqwxQPK7FPcnSAHZf1+_C=qfzR7MLEqdhvtdC-0YzAg@mail.gmail.com
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On Tue, Mar 7, 2017 at 7:47 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> You're right to be confused, because that seems to be a bug in the
> existing code. There seems to be no guarantee that the cheapest
> parallel-safe path will be in the cheapest_parameterized_paths list.
> I'll go fix that.

Okay, Done the simmilar changes in sort_inner_and_outer as well.
>
> As a matter of style, when testing a value of type "bool", write if
> (x) or if (!x). When testing a variable of some other type, say int,
> write if (x == 0) or if (x != 0) or whatever.

Done

Apart from this, there was one problem in match_unsorted_outer (in
v10), Basically, if inner_cheapest_total was not parallel_safe then I
was always getting parallel safe inner. But, we should not do anything
if jointype was JOIN_UNIQUE_INNER, so fixed that also.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

Attachment Content-Type Size
parallel_mergejoin_v11.patch application/octet-stream 13.9 KB

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