I had an interesting case recently. The customer dealing with large MySQL data warehouse had the table which was had data merged into it with INSERT ON DUPLICATE KEY UPDATE statements. The performance was extremely slow. I turned out it is caused by hundreds of daily partitions created for this table. What is the most [...]
table_cache negative scalability
November 16, 2009 By 23 Comments
Couple of months ago there was a post by FreshBooks on getting great performance improvements by lowering table_cache variable. So I decided to investigate what is really happening here. The “common sense” approach to tuning caches is to get them as large as you can if you have enough resources (such as memory). With MySQL [...]
How number of columns affects performance ?
September 28, 2009 By 11 Comments
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 [...]
Multi Column indexes vs Index Merge
September 19, 2009 By 31 Comments
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 [...]
3 ways MySQL uses indexes
September 12, 2009 By 28 Comments
I often see people confuse different ways MySQL can use indexing, getting wrong ideas on what query performance they should expect. There are 3 main ways how MySQL can use the indexes for query execution, which are not mutually exclusive, in fact some queries will use indexes for all 3 purposes listed here.
Give me 8 hours, and I’ll help you build a better application
August 29, 2009 By 4 Comments
I have run into a number of cases recently that all had a similar look and feel. In most of these cases, the symptoms were very complicated, but they boiled down to just a few problems that can be prevented in very simple ways. If you are not doing any of the following three simple [...]
Detailed review of Tokutek storage engine
April 28, 2009 By 21 Comments
(Note: Review was done as part of our consulting practice, but is totally independent and fully reflects our opinion) I had a chance to take look TokuDB (the name of the Tokutek storage engine), and run some benchmarks. Tuning of TokuDB is much easier than InnoDB, there only few parameters to change, and actually out-of-box [...]
Another scalability fix in XtraDB
January 23, 2009 By 13 Comments
Recent scalability fixes in InnoDB and also Google’s and your SMP fixes almost made InnoDB results acceptable in primary key lookups queries, but secondary indexes were forgotten for some time. Now having Dell PowerEdge R900 on board (16CPU cores, 16GB RAM) I have some time for experiments, and I played with queries
1 | SELECT name FROM sbtest WHERE country_id = ? LIMIT 5 |
Should you move from MyISAM to Innodb ?
January 12, 2009 By 59 Comments
There is significant portion of customers which are still using MyISAM when they come to us, so one of the big questions is when it is feasible to move to Innodb and when staying on MyISAM is preferred ? I generally prefer to see Innodb as the main storage engine because it makes life much [...]
High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
We have a lot of customers who do click analysis, site analytics, search engine marketing, online advertising, user behavior analysis, and many similar types of work. The first thing these have in common is that they’re generally some kind of loggable event. The next characteristic of a lot of these systems (real or planned) is [...]
