| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Partition-wise join for join between (declaratively) partitioned tables |
| Date: | 2017-04-20 06:02:07 |
| Message-ID: | 20596.1492668127@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> I don't understand why you think that partition-wise join needs any
> new logic here; if this were a non-partitionwise join, we'd similarly
> need to use the correct operator, but the existing code handles that
> just fine. If the join is performed partition-wise, it should use the
> same operators that would have been used by a non-partitionwise join
> between the same tables.
More to the point, the appropriate operator was chosen by parse analysis.
The planner has *zero* flexibility as to which operator is involved.
BTW, I remain totally mystified as to what people think the semantics of
partitioning ought to be. Child columns can have a different type from
parent columns? Really? Why is this even under discussion? We don't
allow that in old-school inheritance, and I cannot imagine a rational
argument why partitioning should allow it.
regards, tom lane
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