Re: Unhappy about API changes in the no-fsm-for-small-rels patch

On Sat, May 4, 2019 at 2:55 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Fri, May 3, 2019 at 2:14 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Fri, May 3, 2019 at 11:43 AM John Naylor <john.naylor@2ndquadrant.com> wrote:
>
> Attached is a revert patch.  John, can you please once double-check to
> ensure I have not missed anything?
>
> To summarize for everyone:  This patch avoids the fsm creation for
> small relations (which is a small but good improvement as it saves
> space).   This patch was using a process local map to track the first
> few blocks and was reset as soon as we get the block with enough free
> space.   It was discussed in this thread that it would be better to
> track the local map in relcache and then invalidate it whenever vacuum
> frees up space in the page or when FSM is created.   There is a
> prototype patch written for the same, but it is not 100% clear to me
> that the new idea would be a win in all cases (like code complexity or
> API design-wise) especially because resetting the map is not
> straight-forward.  As time was not enough, we couldn't complete the
> patch from all aspects to see if it is really better in all cases.
>
> We have two options (a) revert this patch and try the new approach in
> next release, (b) keep the current patch and replace with the new
> approach if it turns out to be better in next release.
>
> So, do we want to keep this feature for this release?
>
> I am fine going with option (a), that's why I have prepared a revert
> patch, but I have a slight fear that the other option might not turn
> out to be better and even if it is then we can anyway replace it as
> shown in the prototype, so going with option (b) doesn't sound to be
> dumb.
>
> Anybody else wants to weigh in?
>

I understand that we have to take a call here shortly, but as there is
a weekend so I would like to wait for another day to see if anyone
else wants to share his opinion.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com