Sebastian Freundt <hroptatyr(at)gna(dot)org> writes:
> using a highly surjective left (or inner) join to a table reveals data
> loss if the hash join method is used.
In which PG version? Given that you appear to be playing with 8.1devel
code, you might be needing this bug fix:
2005-07-23 22:25 tgl
* src/backend/nodes/tidbitmap.c: Fix logic error in tbm_intersect:
the intersection of a normal page and a lossy page has to be lossy,
because we don't know exactly which tuples on the page should
remain part of the bitmap. Per Jie Zhang.
If not, please send along a self-contained test case.
regards, tom lane