Tag: optimizer

Bushy join trees in Oracle 12.2

There are multiple optimizer features introduced in the Oracle Database 12.2 Release. Bushy Join Trees is the one that I’ll be demonstrating in this post. First, I’ll create four tables with two indexes: create table t1 as select rownum n1,…

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The side effects of drop ‘unused’ index

In this blog post I’ll demonstrate a scenario where dropping a potentially ‘unused’ index can have a negative influence on the optimizer’s cardinality estimation. Having columns with logical correlation and skewed data can cause difficulties for the optimizer when calculating…

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Optimizer Stew – parsing the ingredients to control execution plans

Jared Still, Pythian Principle Consultant and Oracle ACE, explains how to keep track of the different methods used to control Oracle Optimizer execution plans.

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