Greg Stark <gsstark@mit.edu> writes:
> So I'm a bit confused about the term "Clustering". It seems Postgres uses it
> to mean simply ordering the tuple storage within an otherwise normal table.
> However in other databases it seems to mean something more complex.
My take is that "clustering" means not only placing related tuples near
each other, but taking steps to preserve that organization over time.
PG is really misusing the term because our current CLUSTER command does
the first but not the second.
If tuple insertions were to try to preserve the heap ordering induced
by the latest CLUSTER command, then I think we'd have something closer
to what is usually meant by the term.
> I've never used it in Oracle, but from what I read it seems Oracle
> thinks "clustering" means storing the tuples for one table in the heap
> for *another* table entirely.
I think that's an implementation detail rather than the fundamental
meaning.
regards, tom lane