> Based on experience with optimizer improvements across releases of DB
> products (not PostgreSQL, I hastily add), I would be inclined
> to say (from
> bitter experience) that no optimizer is ever truly
> predicatable. The SQL
> programmer has to be given the tools to ensure that a 'bad'
> query can be
> forced to run the same way with each release, and release notes should
> indicate what extra strategies are now available, in case the
> 'bad' query
> can be made better.
Yes, I think syntax to force or disallow a particular index,
choose a join method or order, force/disallow seq scans ...
is sometimes useful.
Even Informix, who always refused to supply such a feature
now has it.
Andreas