DBA Lounge

Yes, More and More and Moore… but Different!

We humans are not able to process large amount of precise data. In any human–readable report, we don’t need more than ten or twenty lines of numbers. Every time we look at processes or data more complex that that, we employ simplifications — graph trends, mind–mapping, aggregations, and so on. How will we make computers process information just as humans do? Perhaps we can find the answer inside ourselves if we figure out how our minds work. We recognize images even though our brain is not capable of processing huge amounts of data in milliseconds.

Oracle Gotcha: Months_between 31-days-per-month assumption

Over-the-Top Tales from the Trenches:: Bringing order to the chaos of everyday DBA life.

Do you want to know a secret? Understanding it will prevent pain and gnashing of teeth, and also leave your face comfortably free of egg. Here it is: Some Oracle functions assume there are 31 days for each month of the year! The moral of the story: be careful when using MONTHS_BETWEEN for fractional dates.

The Fine Art of Baloney Detection: In honour of Dr. Carl Sagan

Carl Sagan is a personal hero of mine. Ten years ago today this gifted communicator died of cancer. And so today the community of bloggers that loved and admired Carl Sagan is having a spontaneous blogathon in his memory. You might ask, what does Carl Sagan have to do with being a good DBA? Believe it or not, a lot. Yes, really.

The Pitfalls of Oracle’s Automatic SGA Management

Oracle thinks it can make queries run better by not having to parse them repeatedly, so it grows the shared pool to keep as many queries as it can. Problem: the shared pool is now 4G+. That takes a while to trawl through, which of course adds to the spins on the library cache lock and pushes up CPU usage. I’m going to get into more detail on this when I have the time, but for this db, I think I’m going to switch to manual SGA and set a hard limit of 500M-1G on the shared pool

MySQL Recipes: Promoting a Slave to Master or Changing Masters

In MySQL–land, failovers for redundancy, disaster recovery, or load balancing are performed by master databases and slave databases, the most popular method using binlog replication. There are a couple more methods of replication which aren’t covered here. Also see the MySQL Replication FAQ. The methods are the same, but the formatting of the procedure(s) are less than ideal.

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