The information about GIST is at
with more on different indexing and sorting schemes at
And there is more interesting reading at
Author: This extraction from an email sent by
Eugene Selkov, Jr. (<email@example.com>)
contains good information
on GiST. Hopefully we will learn more in the future and update this information.
- thomas 1998-03-01
Well, I can't say I quite understand what's going on, but at least
I (almost) succeeded in porting GiST examples to linux. The GiST access
method is already in the postgres tree (src/backend/access/gist).
Examples at Berkeley
come with an overview of the methods and demonstrate spatial index
mechanisms for 2D boxes, polygons, integer intervals and text
(see also GiST at Berkeley).
In the box example, we
are supposed to see a performance gain when using the GiST index; it did
work for me but I do not have a reasonably large collection of boxes
to check that. Other examples also worked, except polygons: I got an
test=> CREATE INDEX pix ON polytmp
test-> USING GIST (p:box gist_poly_ops) WITH (ISLOSSY);
ERROR: cannot open pix
(PostgreSQL 6.3 Sun Feb 1 14:57:30 EST 1998)
I could not get sense of this error message; it appears to be something
we'd rather ask the developers about (see also Note 4 below). What I
would suggest here is that someone of you linux guys (linux==gcc?) fetch the
original sources quoted above and apply my patch (see attachment) and
tell us what you feel about it. Looks cool to me, but I would not like
to hold it up while there are so many competent people around.
A few notes on the sources:
1. I failed to make use of the original (HP-UX) Makefile and rearranged
the Makefile from the ancient postgres95 tutorial to do the job. I tried
to keep it generic, but I am a very poor makefile writer -- just did
some monkey work. Sorry about that, but I guess it is now a little
more portable that the original makefile.
2. I built the example sources right under pgsql/src (just extracted the
tar file there). The aforementioned Makefile assumes it is one level
below pgsql/src (in our case, in pgsql/src/pggist).
3. The changes I made to the *.c files were all about #include's,
function prototypes and typecasting. Other than that, I just threw
away a bunch of unused vars and added a couple parentheses to please
gcc. I hope I did not screw up too much :)
4. There is a comment in polyproc.sql:
-- -- there's a memory leak in rtree poly_ops!!
-- -- CREATE INDEX pix2 ON polytmp USING RTREE (p poly_ops);
Roger that!! I thought it could be related to a number of
back and tried the query. My system went nuts and I had to shoot down
the postmaster in about ten minutes.
I will continue to look into GiST for a while, but I would also
more examples of R-tree usage.