On Mon, Nov 2, 2020 at 10:53 PM Amit Langote <amitlangot...@gmail.com> wrote: > On Mon, Nov 2, 2020 at 10:19 PM Heikki Linnakangas <hlinn...@iki.fi> wrote: > > (/me reads patch further) I presume that's what you referred to in the > > commit message: > > > > > Also, extend this lazy initialization approach to some of the > > > individual fields of ResultRelInfo such that even for the result > > > relations that are initialized, those fields are only initialized on > > > first access. While no performance improvement is to be expected > > > there, it can lead to a simpler initialization logic of the > > > ResultRelInfo itself, because the conditions for whether a given > > > field is needed or not tends to look confusing. One side-effect > > > of this is that any "SubPlans" referenced in the expressions of > > > those fields are also lazily initialized and hence changes the > > > output of EXPLAIN (without ANALYZE) in some regression tests. > > > > > > I'm now curious what the initialization logic would look like, if we > > initialized those fields in ExecGetResultRelation(). At a quick glance > > on the conditions on when those initializations are done in the patch > > now, it would seem pretty straightforward. If the target list contains > > any junk columns, initialize junk filter, and if > > ModifyTable->returningLists is set, initialize RETURNING list. Maybe I'm > > missing something. > > Yeah, it's not that complicated to initialize those things in > ExecGetResultRelation(). In fact, ExecGetResultRelation() (or its > subroutine ExecBuildResultRelation()) housed those initializations in > the earlier versions of this patch, but I changed that after our > discussion about being lazy about initializing as much stuff as we > can. Maybe I should revert that?
Please check the attached if that looks better. -- Amit Langote EDB: http://www.enterprisedb.com
v7-0001-Call-BeginDirectModify-from-ExecInitModifyTable.patch
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v7-0002-Initialize-result-relation-information-lazily.patch
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