Re: KNNGIST next step: adjusting indexAM API

Dimitri Fontaine <dimitri@2ndQuadrant.fr> writes:
> Tom Lane <tgl@sss.pgh.pa.us> writes:
>> Right, AFAIK there is nothing in KNNGIST that would involve an on-disk
>> data change.

> But any external module relying on GiST will have to provide for the new
> function you're thinking about, right? Updating was already needed to
> cope with the newer consistent API, I guess.

ISTM that it should be possible to allow an opclass to not supply the
new hook function if it doesn't support any ordering operators.  So
that's not really a serious problem.  The existing patch approaches
this by having two different APIs for the Consistent function depending
on whether the opclass supports ordering operators or not.  I find that
pretty icky, even though it nominally avoids breaking existing opclass
modules.
        regards, tom lane