Posts Categorized: Pythian

Mystery Solved: Replication lag in InnoDB

While running a backup with XtraBackup against a slave server we noticed that replication was lagging significantly. The root cause wasn’t clear, but we noticed that DML statements from replication were just hanging for a long time. Replication wasn’t always hanging, but it happened so frequently that a 24 hour backup caused replication to lag…

Optimizing your MySQL Tuning Methodology

Optimizing your queries There are two general methods for creating a query plan for a query. A rule-based optimizer goes through your query, sees if you’re doing X or Y, and then optimizes for method A or B depending. Rule-based optimizers grow rather large as there are many possible cases to account for. Sometime in…

Presentations for Ottawa Oracle User Group

The Ottawa Oracle User Group (OOUG) was kind enough to invite me to give presentations for a whole morning. The group was ultra engaged and asked a lot of good questions, so my usual 50-minute Big Data presentation ended up taking 100 minutes, and the rest of the content had to be squeezed a bit. I hope everyone had a good time!

Locks, Latches, Mutexes, and CPU Usage

So how is the actual “waiting on lock” implemented? How does session B, waiting for a transaction to commit started by session A, knows that the resource is free for use? To find out how it is implemented, I have traced Oracle foreground processes. I tried this on Oracle RDBMS running on Linux. This is a excerpt of system calls being executed during a session waiting for a lock…

NoCOUG Contest: a Gentler, Saner Solution

The actual challenge calls for a more generic solution than originally described in the magazine. Because there is no glory in half-solving a problem, I had to come back to it. And because the Great Karmic Balance could probably use it, I thought I could take advantage of the broader scope to produce a solution more geared toward elegance and modernism.

First MySQL/MariaDB/NoSQL Latin American Event

The first MySQL/MariaDB/NoSQL Latin American event is on its way, and Pythian will have a MySQL guy there. Yes, Francisco Bordenave (Team 14 TTL) is going to be one of the speakers. I am presenting a conference about replication in MySQL, how to’s, and what’s new in newer versions. This is a very important event, and many of our friends will be there.

Should your ADR be on Shared Storage?

I was on an Exadata environment with four RAC instances when a fellow DBA created an incident package. It was no big deal, except that part of the adrci packaging procedure was to take a backup of the controlfile and include it in the incident package. Though the package was created successfully, the controlfile never made it.

New and Improved: Here Comes the Flood

In the last few weeks, I launched quite a few small releases to CPAN. Taken separately, they are hardly worth a full blog entry, but taken together, they’ll make for a lovely N&I entry. So if you have been wondering what I’ve been up recently, read more!

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