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SQL Plan Directives in 12cR2. Behavior is different than in 12cR1.

21.12.2016 by Clemens Bleile

During the Frankfurter IT Tage I provided a presentation about SQL Plan Directives and how to reproduce a testcase in a test environment for a plan with used SQL Plan Directives (SPD). In that context I did a couple of(…)

Database Administration & Monitoring

SQL Plan Directives strikes again

04.02.2016 by Oracle Team

By Franck Pachot . 12c SQL Plan Directives, a side effect, a bad application design, a bug... and the occasion to show how to quickly troubleshoot. An application has long response time since 12c migration. No blind guesses, no reason(…)

Database management

How to import SQL Plan Directives

12.06.2015 by Oracle Team

By Franck Pachot . Today I’ve presented SQL Plan Directives at the SOUG Romandie event. I had a question about the import/export of directives by Data Pump. The idea is that a lot of testing has been done on(…)

Database management

Matching SQL Plan Directives and queries using it

18.05.2015 by Oracle Team

By Franck Pachot . This is another blog post I’m writing while reviewing the presentation I’m doing next week forSOUG and next month for DOAG. You have SQL Plan Directives used by several queries that have same(…)

Database management

Matching SQL Plan Directives and extended stats

18.05.2015 by Oracle Team

By Franck Pachot . This year is the year of migration to 12c. Each Oracle version had its CBO feature that make it challenging. The most famous was the bind variable peeking in 9iR2. Cardinality feedback in 11g also(…)

Oracle

Oracle SPD status on two learning paths

19.12.2020 by Oracle Team

By Franck Pachot . I have written a lot about SQL Plan Directives that appeared in 12c. They were used by default and, because of some side effects at the time of 12cR1 with legacy(…)

Oracle

Dynamic Sampling vs. Extended Statistics

14.11.2017 by Oracle Team

By Franck Pachot . On datawarehouse databases, I frequently recommend increasing the level of dynamic sampling because: Queries have complex predicates with AND, OR, IN(), ranges and correlated values for which the optimizer cannot estimate the cardinality properly Queries are(…)

Oracle

Autonomous Database

08.10.2017 by Oracle Team

By Franck Pachot . Larry Ellison has announced Oracle 18c to be the Autonomous Database, the no-human labor, and self-driven, database. Here is a quick recap of what it is behind the marketing words. My opinion only.

Database Administration & Monitoring

Oracle 12cR2 : Optimizer Statistics Advisor

08.05.2017 by Joël Cattin

The Optimizer Statistics Advisor is a new Advisor in Oracle 12.2. The goal of this Advisor is to check the way you gather the statistics on your database, and depending on what is found, it will makes some recommendations(…)

Database Administration & Monitoring

When automatic reoptimization plan is less efficient

02.04.2017 by Oracle Team

By Franck Pachot . 11gR2 started to have the optimizer react at execution time when a misestimate is encountered. Then the next executions are re-optimized with more accurate estimation, derived from the execution statistics. This was called cardinality feedback. Unfortunately,(…)