Can get GiST RECHECK clause to work

Hi everyone,

I'm trying to mark a GiST index as lossy using the RECHECK operator as
part of some work on PostGIS, but what happens is that the original
operator function is never reapplied to the results of the index scan.
The operator class and operator definitions looks like this:

CREATE OPERATOR && (
LEFTARG = GEOMETRY, RIGHTARG = GEOMETRY, PROCEDURE =
geometry_overlap,
COMMUTATOR = '&&',
RESTRICT = postgis_gist_sel, JOIN = positionjoinsel
);

and:

CREATE OPERATOR CLASS gist_geometry_ops
DEFAULT FOR TYPE geometry USING gist AS
OPERATOR 1 << RECHECK,
OPERATOR 2 &< RECHECK,
OPERATOR 3 && RECHECK,
OPERATOR 4 &> RECHECK,
OPERATOR 5 >> RECHECK,
OPERATOR 6 ~= RECHECK,
OPERATOR 7 ~ RECHECK,
OPERATOR 8 @ RECHECK,
FUNCTION 1 ggeometry_consistent (internal,
geometry, int4),
FUNCTION 2 gbox_union (bytea, internal),
FUNCTION 3 ggeometry_compress (internal),
FUNCTION 4 rtree_decompress (internal),
FUNCTION 5 gbox_penalty (internal, internal,
internal),
FUNCTION 6 gbox_picksplit (internal, internal),
FUNCTION 7 gbox_same (box, box, internal);

What I'm expecting is that since RECHECK is specified, PostgreSQL will
identify the index entries using the && operator and then call
geometry_overlap() function with the full tuples from the heap. However,
it seems geometry_overlap() is never called from an index scan made
using the && operator :( Can anyone point out where I'm going wrong?

Many thanks,

Mark.

---

Mark Cave-Ayland
Webbased Ltd.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England

Tel: +44 (0)1752 764445
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