Tom Lane wrote:
>
> Hannu Krosing <hannu@tm.ee> writes:
> > Just out of curiosity - does CLUSTER currently "practically rebuild
> > a tables representation" ?
>
> CLUSTER currently *loses* most of a table's representation :-(.
> It needs work.
at least \h CLUSTER in psql seems to imply that it is OK to use CLUSTER
?
Do we have some indication of last CLUSTER command (like an OID column
of
cluster index field) in pg_relation so that VACUUM caould make better
decisions when moving tuples ?
> But since the whole point of CLUSTER is to physically rearrange the
> tuples of a table, it seems to me that it's in a different category
> from VACUUM anyway.
Another way to look at it is as "VACUUM LOCK AND PERFORM HEAVY
REARRANGEMENTS"
Or does the current implementation actually do the rearrangement by
appending all out-of-index-order tuples to the end and _not_ clean up
unused space requiring an additional vacuum after CLUSTER ?
--------------
Hannu