Re: [HACKERS] How does postgres store the join predicate for arelation in a given query

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От Gourav Kumar
Тема Re: [HACKERS] How does postgres store the join predicate for arelation in a given query
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Msg-id CAPzqDmgxd-q7JgSg00hdyviuNVHpraGtpqs-7+RwaONvfmAK_Q@mail.gmail.com
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Ответ на Re: [HACKERS] How does postgres store the join predicate for a relation in a given query  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [HACKERS] How does postgres store the join predicate for arelation in a given query
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Well for this given query it is possible. I haven't come across any such query yet.

Possibly because I am more concerned about the TPCDS and TPCH benchmarks, where it's less likely to occur.

On 13 October 2017 at 00:52, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Gourav Kumar <gourav1905@gmail.com> writes:
> A Join clause/predicate will only mention 2 relations. It can't have 3 or
> more relations.

Really?  What of, say,

        select ... from a,b,c where (a.x + b.y) = c.z;

                        regards, tom lane



--
Thanks,
Gourav Kumar
Computer Science and Automation
Indian Institute of Science

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