October 20, 2014

Admin notice: comments again broken

(This note should not go to PlanetMySQL, sorry if it goes). We again have problem with comments to blog posts. It’s technical problem, we did upgrade some components and it seems it affected captcha. We are working on fix. We are sorry for the inconvenience and thank for reports about the problem.

Quick comparison of MyISAM, Infobright, and MonetDB

Recently I was doing a little work for a client who has MyISAM tables with many columns (the same one Peter wrote about recently). The client’s performance is suffering in part because of the number of columns, which is over 200. The queries are generally pretty simple (sums of columns), but they’re ad-hoc (can access […]

How number of columns affects performance ?

It is pretty understood the tables which have long rows tend to be slower than tables with short rows. I was interested to check if the row length is the only thing what matters or if number of columns we have to work with also have an important role. I was interested in peak row […]

Why InnoDB index cardinality varies strangely

This is a very old draft, from early 2007 in fact. At that time I started to look into something interesting with the index cardinality statistics reported by InnoDB tables. The cardinality varies because it’s derived from estimates, and I know a decent amount about that. The interesting thing I wanted to look into was […]

InnoDB/XtraDB Training in New York City!

Our Santa Clara/San Francisco training went great – 100% of survey respondents said they would recommend the same course to a friend.  I’m pleased to announce that such an opportunity exists – our next training location will be New York City on October 30, 2009. We’ve booked a training venue in the financial district of […]

Speaking at Highload.ru

This is a quick announcement to say that I’ll be speaking at HighLoad++ this year (October 12-14 in Moscow).  I’ll be presenting on a few topics: MySQL Performance Tuning (Conference Session) Quick Wins with Third Party Patches for MySQL (Conference Session) Performance Optimization for MySQL with InnoDB and XtraDB * (Full day class) This will […]

Guidance for MySQL Optimizer Developers

I spend large portion of my life working on MySQL Performance Optimization and so MySQL Optimizer is quite important to me. For probably last 10 years I chased first Monty and later Igor with Optimizer complains and suggestions. Here are some general ideas which I think can help to make optimizer in MySQL, MariaDB or […]

Multi Column indexes vs Index Merge

The mistake I commonly see among MySQL users is how indexes are created. Quite commonly people just index individual columns as they are referenced in where clause thinking this is the optimal indexing strategy. For example if I would have something like AGE=18 AND STATE=’CA’ they would create 2 separate indexes on AGE and STATE […]

How to generate per-database traffic statistics using mk-query-digest

We often encounter customers who have partitioned their applications among a number of databases within the same instance of MySQL (think application service providers who have a separate database per customer organization … or wordpress-mu type of apps). For example, take the following single MySQL instance with multiple (identical) databases:

Which adaptive should we use?

As you may know, InnoDB has 2 limits for unflushed modified blocks in the buffer pool. The one is from physical size of the buffer pool. And the another one is oldness of the block which is from the capacity of transaction log files. In the case of heavy updating workload, the modified ages of […]