Or expansion: Linear
PREAMBLE In the previous article, we discussed the two-pass technique used by Oracle to evaluate the cost of the different OR-Expansion states. We have shown that this technique evaluates the cost of...
View Articleenq: TM – contention [mode=3/5]
Here is a simple but very practical example to show how to identify the root cause of a sudden and intermittent lock that considerably affects the proper functioning of a database: SQL> @dashtopmho...
View ArticleForce matching signature
It often happens that changes are implemented in new Oracle releases without most (if not all) DBAs and developers being informed. Among those changes, introduced most probably in version 19.13, is a...
View ArticleSPM baseline and historical execution plans
I have often wondered why when we consult a past execution plan that is protected by an SPM baseline, there is no Note at the bottom of that execution plan showing the use of that SPM? SQL> select...
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