Ok, I’ve wanted to write this blog entry for a long time – and now it’s time!
Most of my blog readers (thank you!) are performance-minded computer enthusiasts, who care about efficiency and optimization. You’ve been tuning SQL execution plans, instance and OS configuration so that your sessions would achieve the same results with less work and also with less waiting!
Last week (March 2012), I was conducting Advanced RAC Training online. During the class, I was recreating a ‘gc buffer busy’ waits to explain the concepts and methods to troubleshoot the issue.
Let’s define these events first. Event ‘gc buffer busy’ event means that a session is trying to access a buffer,but there is an open request for Global cache lock for that block already, and so, the session must wait for the GC lock request to complete before proceeding. This wait is instrumented as ‘gc buffer busy’ event.
DBA? Why you should skip Codecademy and give Perl a try There has been a lot of publicity recently about the increased interest in learning to ‘code’, partly brought about by the high profile (and very innovative) Codecademy . This organization offers free online courses focusing on Java, one of the most popular and accessible [...]
If you drop a unique or primary key constraint the index that supports it may be dropped at the same time – but this doesn’t always happen. Someone asked me recently if it was possible to tell whether or not an index would be dropped without having to find out the hard way by dropping the constraint. The answer is yes – after all, Oracle has to make a decision somehow, so if we can find out how it makes the decision we can predict the decision.
When performance data is periodically collected (i.e., snapshotted) and stored, the question undoubtedly will cross our minds, "Is the stored value correct at the beginning or the ending snapshot time?" In relation to Oracle's AWR system and specifically the dba_hist_sysstat table, this is what this posting is all about.
A common DBA task is to perform regular clones and database refreshes of the production database for the purpose of setting up training or test or development environments.
If we are having a physical standby Data Guard environment, then we can easily offload the potentially I/O and CPU intensive backup process required for creating these clone or duplicate databases to the standby site.
Here are a few examples of using the physical Standby database in a Data Guard environment to create a clone of the primary production database.