May 22, 2013

Innodb Table Locks

July 31, 2012 By 4 Comments

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 [...]

Filed Under: Insight for DBAs, MySQL

High Rate insertion with MySQL and Innodb

January 7, 2011 By 17 Comments

I again work with the system which needs high insertion rate for data which generally fits in memory. Last time I worked with similar system it used MyISAM and the system was built using multiple tables. Using multiple key caches was the good solution at that time and we could get over 200K of inserts/sec. [...]

Filed Under: Benchmarks, MySQL Tagged With:

Why you should ignore MySQL’s key cache hit ratio

February 28, 2010 By 28 Comments

I have not caused a fist fight in a while, so it’s time to take off the gloves. I claim that somewhere around of 99% of advice about tuning MySQL’s key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key buffer hit ratio, and [...]

Filed Under: Insight for DBAs, MySQL Tagged With: , , ,

Finding your MySQL High-Availability solution – The questions

October 16, 2009 By 36 Comments

After having reviewed the definition my the previous post (The definitions), the next step is to respond to some questions. Do you need MySQL High-Availability? That question is quite obvious but some times, it is skipped. It can also be formulated “What is the downtime cost of the service?”. In the cost, you need to [...]

Filed Under: Insight for DBAs, MySQL Tagged With:

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.

Filed Under: Insight for Developers Tagged With:

Fix of InnoDB/XtraDB scalability of rollback segment

January 18, 2009 By 9 Comments

Recently I wrote about InnoDB scalability on 24-core box, and we made research of scalability problems in sysbench write workload (benchmark emulates intensive insert/delete queries). By our results the problem is in concurrency on rollback segment, which by default is single and all transactions are serialized accessing to segment. Fortunately InnoDB internally has mechanism to [...]

Filed Under: Benchmarks, Percona Software Tagged With: ,

How much overhead DRDB could cause ?

June 2, 2008 By 4 Comments

I was working with the customer today investigating MySQL over DRBD performance issues. His basic question was why there is so much overhead with DRBD in my case, while it is said there should be no more than 30% overhead when DRBD is used. The truth is – because how DRBD works it does not [...]

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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 [...]

Filed Under: Benchmarks Tagged With: , ,

Managing Slave Lag with MySQL Replication

October 12, 2007 By 15 Comments

The question I often get is how far MySQL may fall behind and how to keep replication from lagging. The lag you will see will vary a lot from application to the application and from load to load. Plus what is the most important within same application the lag will likely have spikes – most [...]

Filed Under: Insight for DBAs Tagged With:

MyISAM Scalability and Innodb, Falcon Benchmarks

October 12, 2007 By 10 Comments

We many times wrote about InnoDB scalability problems, this time We are faced with one for MyISAM tables. We saw that several times in synthetic benchmarks but never in production, that’s why we did not escalate MyISAM scalability question. This time working on the customer system we figured out that box with 1 CPU Core [...]

Filed Under: Uncategorized Tagged With: , , , ,
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