On 2018/04/24 13:29, Ashutosh Bapat wrote: > On Mon, Apr 23, 2018 at 6:45 PM, Amit Langote <amitlangot...@gmail.com> wrote: >> On Mon, Apr 23, 2018 at 8:25 PM, Ashutosh Bapat wrote: >>> On Mon, Apr 23, 2018 at 3:44 PM, Amit Langote wrote: >>>> Hi. >>>> >>>> acquire_inherited_sample_rows() currently uses equalTupleDescs() being >>>> false as the condition for going to tupconv.c to determine whether tuple >>>> conversion is needed. But equalTupleDescs() will always return false if >>>> it's passed TupleDesc's of two different tables, which is the most common >>>> case here. So I first thought we should just unconditionally go to >>>> tupconv.c, but there is still one case where we don't need to, which is >>>> the case where the child table is same as the parent table. However, it >>>> would be much cheaper to just check if the relation OIDs are different >>>> instead of calling equalTupleDescs, which the attached patch teaches it to >>>> do. >>> >>> We want to check whether tuple conversion is needed. Theoretically >>> (not necessarily practically), one could have tuple descs of two >>> different tables stamped with the same tdtypeid. From that POV, >>> equalTupleDescs seems to be a stronger check than what you have in the >>> patch. >> >> If I'm reading right, that sounds like a +1 to the patch. :) > > Not really! To make things clear, I am not in favour of this patch.
Oh okay. I read your last sentence as "equalTupleDescs() seems to be a stronger check than needed" (which is how I see it), but apparently that's not what you meant to say. Anyway, thanks for clarifying. Regards, Amit
