Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
> 2010/1/19 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> AFAICS that doesn't mean it can't be the
>> canonicalized form of the sort key. If a column is dropped out of the
>> canonical sort key then it's simply redundant, and hence not relevant to
>> determining the range.
> Yeah, that's my point, too. The planner has to distinguish "four" from
> sort pathkeys and to teach the executor the simple information which
> column should be used to determine frame. I was bit wrong because some
> of current executor code isn't like it, like using ordNumCols == 0 to
> know whether partition equals to frame, though....
BTW, watch out for the possibility that the canonicalized key is empty.
This isn't an error case --- what it means is that the planner has
proven that all the rows have equal sort key values, so there's no
need to compare anything.
regards, tom lane
In response to
pgsql-hackers by date
|Next:||From: Tom Lane||Date: 2010-01-19 01:37:17|
|Subject: Re: plpgsql: open for execute - add USING clause |
|Previous:||From: Robert Haas||Date: 2010-01-19 00:49:59|
|Subject: Re: parallel regression test output|