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When your projection is not cost-free
First of all I have to admit that the title of this post is a bit misleading - the projection is almost never "cost-free". Indirectly cost will be generated by accessing rows from row sources to obtain...
View ArticleHeuristic TEMP Table Transformation
There are at least three different ways how the Oracle optimizer can come up with a so called TEMP table transformation, that is materializing an intermediate result set:- As part of a star...
View ArticleCombining Features - Wrong Results With Scalar Subquery Caching
Quite often you can get into trouble with Oracle when you start combining different features.In this case of one my clients it is the combination of user-defined PL/SQL functions that can raise...
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