Suppose you have turned on innodb_file_per_table (which means that each table has its own tablespace), and you have to drop tables in a background every hour or every day. If its once every day then you can probably schedule the table dropping process to run during off-peak hours. But I have seen cases where the [...]
DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
New distribution of random generator for sysbench – Zipf
May 9, 2012 By 3 Comments
Sysbench has three distribution for random numbers: uniform, special and gaussian. I mostly use uniform and special, and I feel that both do not fully reflect my needs when I run benchmarks. Uniform is stupidly simple: for a table with 1 mln rows, each row gets equal amount of hits. This barely reflects real system, [...]
Impact of the sort buffer size in MySQL
October 25, 2010 By 8 Comments
The parameter sort_buffer_size is one the MySQL parameters that is far from obvious to adjust. It is a per session buffer that is allocated every time it is needed. The problem with the sort buffer comes from the way Linux allocates memory. Monty Taylor (here) have described the underlying issue in detail, but basically above [...]
UDF -vs- MySQL Stored Function
September 6, 2010 By 8 Comments
Few days ago I was working on a case where we needed to modify a lot of data before pushing it to sphinx – MySQL did not have a function to do the thing so I thought I’ll write MySQL Stored Function and we’ll be good to go. It worked! But not so well really [...]
How innodb_open_files affects performance
November 18, 2009 By 4 Comments
Recently I looked at table_cache sizing which showed larger table cache does not always provides the best performance. So I decided to look at yet another similar variable – innodb_open_files which defines how many files Innodb will keep open while working in innodb_file_per_table mode. Unlike MyISAM Innodb does not have to keep open file descriptor [...]
Looking at Redis
August 27, 2009 By 27 Comments
Recently I had a chance to take a look at Redis project, which is semi-persistent in memory database with idea somethat similar to memcache but richer feature set. Redis has simple single process event driven design, which means it does not have to deal with any locks which is performance killer for a lot of [...]
Just do the math!
July 6, 2009 By 4 Comments
One of the most typical reasons for performance and scalability problems I encounter is simply failing to do the math. And these are typically bad one because it often leads to implementing architectures which are not up for job they are intended to solve. Let me start with example to make it clear. Lets say [...]
How much space does empty Innodb table take ?
December 16, 2008 By 7 Comments
How much space would empty MyISAM table take ? Probably 8K for .frm file, 1KB for .MYI file and 0 for MYD file. .MYI file can be larger if you have many indexes. How much space will Innodb take:
Beware of MyISAM Key Cache mutex contention
August 12, 2008 By 10 Comments
Today I was working with the client loading data to MyISAM tables at very high rate. Hundreds of millions rows are loaded daily into single MySQL instance with bursts up to 100K of records/sec which need to be inserted (in the table with few indexes). It was good not all records had to go to [...]
MySQL Performance on Memory Appliance
March 31, 2008 By 23 Comments
Recently I have had a chance to check out MySQL Performance on “Memory Appliance” by Violin Memory which can be used as extremely high speed storage system. I helped Violin Memory to optimize MySQL for customer workload and Violin memory and also had a chance to do some benchmarks on my own. 2*Quad Core Xeon [...]
