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

Andres Freund <andres@anarazel.de> writes:
> On 2019-04-16 14:31:25 -0400, Tom Lane wrote:
>> This can only work at all if an inaccurate map is very fail-soft,
>> which I'm not convinced it is

> I think it better needs to be fail-soft independent of this the no-fsm
> patch. Because the fsm is not WAL logged etc, it's pretty easy to get a
> pretty corrupted version. And we better deal with that.

Yes, FSM has to be fail-soft from a *correctness* viewpoint; but it's
not fail-soft from a *performance* viewpoint.  It can take awhile for
us to self-heal a busted map.  And this fake map spends almost all its
time busted and in need of (expensive) corrections.  I think this may
actually be the same performance complaint you're making, in different
words.

            regards, tom lane