"Gary Doades" <gpd@gpdnet.co.uk> writes:
> As a test in PosgreSQL I issued a statement to update a single column
> of a table containing 2.8 million rows with the values of a column in
> a table with similar rowcount. Using the above spec I had to stop the
> server after 17 hours. The poor thing was thrashing the hard disk and
> doing more swapping than useful work.
This statement is pretty much content-free, since you did not show us
the table schemas, the query, or the EXPLAIN output for the query.
(I'll forgive you the lack of EXPLAIN ANALYZE, but you could easily
have provided all the other hard facts.) There's really no way to tell
where the bottleneck is. Maybe it's a kernel-level issue, but I would
not bet on that without more evidence. I'd definitely not bet on it
without direct confirmation that the same query plan was used in both
setups.
regards, tom lane