October 24, 2014

Adventures in archiving

One of our Remote DBA service clients recently had an issue with size on disk for a particular table; in short this table was some 25 million rows of application audit data with an on disk size of 345GB recorded solely for the purposes of debugging which may or may not occur. Faced with the task of […]

MySQL Indexing Best Practices: Webinar Questions Followup

I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others are better answered in writing anyway. Q: One developer on our team wants to replace longish (25-30) indexed varchars with […]

Innodb Table Locks

Innodb uses row level locks right ? So if you see locked tables reported in SHOW ENGINE INNODB STATUS you might be confused and rightfully so as Innodb table locking is a bit more complicated than traditional MyISAM table locks. Let me start with some examples. First lets run SELECT Query:

As you can […]

Statement based replication with Stored Functions, Triggers and Events

Statement based replication writes the queries that modify data in the Binary Log to replicate them on the slave or to use it as a PITR recovery. Here we will see what is the behavior of the MySQL when it needs to log “not usual” queries like Events, Functions, Stored Procedures, Local Variables, etc. We’ll […]

What’s up with HandlerSocket?

I’ve presented at two different venues about HandlerSocket recently and the number one question that always arises is: Why hasn’t HandlerSocket become more popular than it is? Considering how fast and awesome HandlerSocket is, it’s not seeing as rapid adoption as some might expect. I theorize that there are five reasons for this:

Moving from MyISAM to Innodb or XtraDB. Basics

I do not know if it is because we’re hosting a free webinar on migrating MyISAM to Innodb or some other reason but recently I see a lot of questions about migration from MyISAM to Innodb. Webinar will cover the process in a lot more details though I would like to go over basics in […]

Drilling down to the source of the problem

I had an interesting tuning case few days ago. The system serving high traffic using Innodb tables would be stalling every so often causing even very simple queries both reads and writes taking long time to complete, with progress almost paused (dropping from thousands to tens of queries per second). On the surface the problem […]

Can having information public hurt consulting business ?

People frequently ask me if the fact we keep information public can hurt our consulting business ? Lets keep aside for the moment amount of new business publishing this information brings to us but think it also have significant negative effect because people find information on MySQL Performance Blog and use it instead of purchasing […]

Heikki Tuuri answers to Innodb questions, Part II

I now got answers to the second portions of the questions you asked Heikki. If you have not seen the first part it can be found here. Same as during last time I will provide my comments for some of the answers under PZ and will use HT for original Heikkis answer. Q26: You also […]

Hacking to make ALTER TABLE online for certain changes

Suppose you want to remove auto_increment from 100G table. No matter if it’s InnoDB or MyISAM, you’d usually ALTER TABLE huge_table CHANGE id id int(6) NOT NULL and then wait hours for table rebuild to complete. If you’re unlucky i.e. you have a lot of indexes and not too much RAM – you could end […]