When you develop an application that uses a database, one of the topics you need to consider is how to connect to the database. Some application use a one-to-one connection,
Category: Database Tuning
Checking SQL Progress in OracleChecking SQL Progress in Oracle
Checking an SQL statement progress is never easy. There are so many parameters that affect your execution time and estimates are never correct. So in this post I’ll mention a
High CPU With Queries Without Bind VariablesHigh CPU With Queries Without Bind Variables
Performance problems can be tricky, and everyone has a different method to approach them depending on the exact issue. In this case I’d like to cover a specific case of
Did You Know #35 – New Child Cursor Creation ReasonDid You Know #35 – New Child Cursor Creation Reason
In many cases we see a new child cursor for existing SQL. You can see the children and their information in V$SQL (where CHILD_NUMBER identifies the child). To see the
Using SPM to Control A Single SQL Execution PlanUsing SPM to Control A Single SQL Execution Plan
SQL Plan Management (SPM) is a powerful tool. It can do many things to control and evolve SQL execution plans to allow the most stable system. In this scenario I’ll
Ansi Joins and ORA-25154Ansi Joins and ORA-25154
For one of my projects I needed to create all kind of dynamic queries and execute them against different tables. During this step I decided to use ansi joins even
Strange Index BehaviorStrange Index Behavior
During a performance problem I had with a query I wanted to create an index on the table. Since this was a large table I wanted the index to include
Top-N QueriesTop-N Queries
This is an old story. It started in 2015 when I found a problem with TOP-N query performance. I wrote a blog post about it and later an update. Here
When Even Histograms Can't HelpWhen Even Histograms Can't Help
Here is an interesting optimizer case where updated statistics and histograms cannot solve the performance problem. This might be an uncommon case, but it happened for one of my clients
Bug When Patching ProductionBug When Patching Production
I had a bad night last Thursday.After patching two test RAC databases and one production RAC with 180417 DB Bundle Patch (and some one-offs), I got to the point where