Re: Allow GiST opcalsses without compress\decompres functions

Andrew Borodin <borodin(at)octonica(dot)com> writes:
> Maybe we should make compress\decompress functions optional?

1. You'll need to adjust the documentation (gist.sgml) not just the code.

2. If compress/decompress are omitted, then we could support index-only
scans all the time, that is a no-op fetch function would work. The
patch should cover that interaction too.

3. Personally I wouldn't bother with the separate compressed[] flags,
just look at OidIsValid(giststate->compressFn[i].fn_oid).

4. I don't think you thought very carefully about the combinations
where only one of the two functions is supplied. I can definitely
see that compress + no decompress could be sensible. Less sure
about the other case, but why not allow it? We could just say that
an omitted function is taken to represent a no-op transformation.

Please add this to the next commitfest.

regards, tom lane