
> 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

Wed, 26 Jan 2000 13:25:55 +0100
Zeugswetter Andreas SB <ZeugswetterA@wien.spardat.at>
AW: AW: AW: [HACKERS] Some notes on optimizer cost estimates 