size of data stored in gist index

Gerhard Heift <ml-postgresql-20081012-3518@gheift.de> writes:

I try to index histograms in my table. For this I uses the cube contrib
module in which I removed the dimension check. If the cube has more than
255 dimensions, for example 256 ^= 4 + 4 + 256 * 2 * 8 = 4104 bytes, this
data can not be stored in the gist index any more. If I try it, I get the
following error:

PANIC: failed to add item to index page in "histogram_idx"

Do I have to compress the data in any way or is it possible, to store index
data with this huge size?

Well, if you're going to turn cube into an unlimited-size datatype,
it would behoove you to make its compress and decompress routines
do something.

Still, it seems like gist ought to defend itself a bit better against
ill-considered datatypes. Maybe put a check in gistFormTuple to verify
that the tuple isn't larger than can fit on one page? Or is there a
better place to check it?

regards, tom lane