Re: GiST index on data types that require compression

Dave Blasby <dblasby(at)refractions(dot)net> writes:
> So far, it doesnt work. Only one of my GiST support functions is called
> (the compress function), after that I get the error message:
> # create index qq on tp3 using gist (the_geom gist_geometry_ops) with
> (islossy);
> ERROR: index_formtuple: data takes 8424504 bytes, max is 8191

It looks like the GIST code expects your compress function to give back
a varlena datatype, not the fixed-length type you are actually handing
back. The ridiculous length comes from interpreting the first word
of your BOX3D as a length.

There are/were provisions in the GIST code for having the compress
function emit a different datatype than it takes in, but I think they
are incomplete or broken. Might be easiest to produce a varlena result
for now.

regards, tom lane