On Sun, Oct 4, 2020 at 11:44 AM Amit Langote <amitlangote09@gmail.com> wrote:
> On Fri, Sep 11, 2020 at 7:20 PM Amit Langote <amitlangote09@gmail.com> wrote:
> > Here are the commit messages of the attached patches:
> >
> > [PATCH v3 1/3] Overhaul how updates compute a new tuple
>
> I tried to assess the performance impact of this rejiggering of how
> updates are performed. As to why one may think there may be a
> negative impact, consider that ExecModifyTable() now has to perform an
> extra fetch of the tuple being updated for filling in the unchanged
> values of the update's NEW tuple, because the plan itself will only
> produce the values of changed columns.
>
...
> It seems clear that the saving on the target list computation overhead
> that we get from the patch is hard to ignore in this case.
>
> I've attached updated patches, because as Michael pointed out, the
> previous version no longer applies.
Rebased over the recent executor result relation related commits.
--
Amit Langote
EDB: http://www.enterprisedb.com
