On Wed, Oct 11, 2006 at 12:40:42PM -0400, Gregory Stark wrote:
> poorly written query. In fact Oracle is going in the opposite direction of
> even relying on hints internally. Its plan stability feature depends on
> generating and storing hints internally associated with every query.
But IBM, whose DB2 planner and optimiser is generally regarded as way
better than Oracle's (at least by anyone I know who's used both),
doesn't like hints. The IBM people all say the same thing Tom has
said before: that the work to design the thing correctly is better
spent making the planner and optimiser parts smarter and cheaper,
because out of that work you also manage not to have the DBA
accidentally mess things up by simple-minded rule-based hints. (Note
that I'm not trying to wade into the actual argument; I'm just
pointing out that even the biggest industry people don't agree on
this point.)
A
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