Oracle

How To Improve SQL Statements Performance: Using SQL Plan Baselines

The performance of any Oracle database heavily relies on query execution(s). The reasons for any SQL statement’s execution plan changes could include a variety of actions, like gathering optimizer statistics (table, index, schema etc.)  changing optimizer parameters, schema definitions, adding indexes etc.  As experienced Oracle DBAs, we should be aware of the fact that the…

Do AWR Reports Show the Whole Picture?

AWR report is a great source of aggregated information on top activities happening in our databases. I use data collected in AWR quite often, and obviously the easiest way of getting the data out from the AWR is by running the AWR report. In most cases that’s not an issue, but there are certain scenarios when…

Disabling Triggers in Oracle 11.2.0.4

Yes you can still disable triggers per-session in Oracle 11.2.0.4, but you have to have a GoldenGate license, set the enable_goldengate_replication parameter, use a program name that starts with replicat, and set your module to OGG.

Statistics gathering and SQL Tuning Advisor

Our monitoring software found a long running job on one of our client’s databases. The job was an Oracle’s auto task running statistics gathering for more than 3 hours. I was curious to know why it took so long and used a query to ASH to find out the most common SQL during the job…

Do you have enough Redo?

The question of whether a database has enough redo logs available is quite common. The documentation suggests to use FAST_START_MTTR_TARGET and V$INSTANCE_RECOVERY.OPTIMAL_LOGFILE_SIZE to identify “the optimal” redo log size based on the target recovery time. I’ve never used it and can’t comment if it is a correct/reasonable way or not. The easiest way to identify…

How to recover a subset of an Oracle database

Today’s blog post will discuss how to recover a subset of an Oracle database. Many of you would have come across different recovery scenarios, but I’ll be talking about a very different one that happened to me. The following are the details after receiving a call from a client, and checking the environment myself. i) This…

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