Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> writes:
> We have a problem as soon as somebody tries to delete a lot of rows from
> a big table. We cannot possibly extend the memory requirements forever,
> so we need to spill to disk without having an in-shared-memory index.
Yes. I'm not sure that I see the point of the in-memory index at all...
there is some intermediate regime where it would improve performance,
but it surely does not solve the basic problem that shared memory is
finite.
Maybe something involving lossy storage would work? Compare recent
discussions about lossy bitmaps generated from index scans.
regards, tom lane