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TKPROF New Features in 11gR2 – Release 11.2.0.1

While writing a post about the TKPROF new features in 11.2.0.2 I noticed that I didn’t write one about an important change introduced in 11.2.0.1. So, before finishing the other one, let’s have a look to what changed in 11.2.0.1.
One problem with TKPROF up to 11gR1 is that when the AGGREGATE parameter is set to [...]

Evolution of a SQL Plan Baseline Based on a DELETE Statement

During an evolution the database engine compares the performance of two execution plans. The aim is to find out which one provides the better performance. For that purpose it has to run the SQL statement on which the SQL plan baseline is based and compare some execution statistics. The following output of the DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE function [...]

Optimizer Mode Mismatch Does Not Prevent Sharing of Child Cursor!?!?

The aim of this post is to describe a strange (buggy) situation that I observed recently. But before doing that, I shortly summarize what a parent cursor and a child cursor are as well as when they can be shared. By the way, I borrowed this description from the pages 20/21 of my book. Hence, [...]

Analyzing a SQL Trace File with SQL Statements

As of Oracle Database 11g the DBMS_SQLTUNE package provides the SELECT_SQL_TRACE function. Its purpose is to load the content of a SQL trace file into a SQL tuning set. But, as it often happens, a feature can be (mis)used for another purpose. The aim of this post is to show how to take advantage of [...]

Inserts Experiencing an Increasing CPU Consumption

Last week I had to analyze a strange performance problem. Since the cause/solution was somehow surprising, at least for me, I thought to share it with you.
Let me start by quickly describing the setup and what was done to reproduce the problem:

Database version: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 (64-bit)
Operating system: Solaris 10 (SPARC)
To [...]