Re: Unknown SQL

Vadim Tropashko wrote:
[Performance of views]
> You are both correct (or wrong;-). View merging merges the body of the
 view to
> the body of the query. Optimizer then consideres the merge as a single
 query.
> This allows the optimizer to consider efficient join orders and index
 access
> paths. However, not every view is mergeable. What views are not mergeable
 in
> Oracle8, for example?
> - outer joins to views containing correlated subqueries
> - outer joins to views containing column concatenations
> - aggregates
> - union, minus, intesect
> - group by
> - distinct

Thank you very much for the clarification. The views we experimented with were full of GROUP BY clauses.

Kind regards,
Carl Received on Sun Jul 22 2001 - 01:26:55 CEST