Dear David, thank you for the detailed response.
I understand your concerns, so I have rethought my approach a bit and would like to discuss,
in general terms, the concept that I would try to implement.
The ability to define a B-tree operator class (opclass) in the clause:
`PARTITION BY RANGE ( { column_name | ( expression ) } [ opclass ] [, ...] )`
allows partitioning over a fairly broad class of sets with a defined order relation.
For example, one can obtain an elegant example using an extension
for ordinary fractions (p/q) represented as `row(p,q)` with a natural
B-tree operator class for the order relation of ordinary fractions:
```sql
drop table if exists axis cascade;
create table axis (
id serial,
key fraction,
label text
) partition by range (key fraction_ops);
create table segment_1 partition of axis for values from ((0,1)::fraction) to ((1,3)::fraction);
create table segment_2 partition of axis for values from ((2,5)::fraction) to ((4,5)::fraction);
create table segment_3 partition of axis for values from ((15,45)::fraction) to ((2,5)::fraction);
-- segment_1,2,3 : [0, 1/3], [2/5, 4/5], [1/3, 2/5], where 15/45 == 1/3
insert into axis(key,label) select (1,5)::fraction, '1/5';
-- insert to segment_1
insert into axis(key,label) select (1,2)::fraction, '1/2';
-- insert to segment_2
insert into axis(key,label) select (1,3)::fraction, '1/3';
-- insert to segment_3
```
However, for multidimensional data structures where one desires
a multidimensional partitioning key using a B-tree, the necessary ordering cannot be established.
It is easy to prove that when attempting to introduce
the concept of "to the left" (less than) / "to the right" (greater than) for rectangles on a plane,
the transitivity of such a relation is violated.
To achieve the intended goal,
it would likely be necessary to use the GiST access method.
According to the documentation, however,
only B-tree is applicable when defining an operator class for a range partitioning key.
**Proposal:** Make GiST available for partitioning in the `opclass` clause of `PARTITION BY RANGE`.
John.
