> > I can find very little information on hot updates but I found this:
> http://archives.postgresql.org/pgsql-patches/2006-11/msg00059.php
> >
> > It states, "This design optimizies the updates when none of the
index
> columns are modified and length of the tuple remains the same after
> update."
> >
> > How can a row's length change? I think it must mean the size (in
bytes)
> of the row remains the same.
> >
>
> I bet you are looking at an old design. That has undergone many
> changes and the current implementation does not have any restriction
> about the row length changes. But a necessary condition is to have
> enough free space in the block (and of course not changing any index
> columns).
>
> You can find the latest README in the source code under
> src/backend/access/heap/README.HOT
>
I'm using 8.3.1 on Solaris and I just tried this:
CREATE TABLE test (a int) WITH (hot_update='true');
It fails with:
ERROR: unrecognized parameter "hot_update"
Is a hot update automatic in 8.3.x and that is why there isn't any
formal documentation other than what is in the source code?
Jon
