| From: | Gourav Kumar <gourav1905(at)gmail(dot)com> |
|---|---|
| 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> |
| Subject: | Re: How does postgres store the join predicate for a relation in a given query |
| Date: | 2017-10-12 19:30:30 |
| Message-ID: | CAPzqDmgxd-q7JgSg00hdyviuNVHpraGtpqs-7+RwaONvfmAK_Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
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(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Gourav Kumar <gourav1905(at)gmail(dot)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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