Author: Vyacheslav Rasskazov

Creating Ansible Custom Module for AWR Report Generation

Creating AWR reports is a common task for many DBAs. At times, you may need to generate multiple AWR reports from multiple databases for performance audit; Ansible allows you to automate these types of tasks. You can, for example, generate…

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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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Performance Problems with Dynamic Statistics in Oracle 12c

I’ve been making some tests recently with the new Oracle 12.1.0.2 In-Memory option and have been faced with an unexpected  performance problem.  Here is a test case: Waiting for in-memory segment population: Now let’s make a simple two table join:…

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OLTP type 64 compression and ‘enq: TX – allocate ITL entry’ on Exadata

Recently we’ve seen a strange problem with the deadlocks at the client database on Exadata, Oracle version 11.2.0.4 . Wait events analysis showed that sessions were waiting for “enq: TX – allocate ITL entry” event. It was strange because there…

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