July 30, 2014

MySQL and the SSB – Part 2 – MyISAM vs InnoDB low concurrency

This blog post is part two in what is now a continuing series on the Star Schema Benchmark. In my previous blog post I compared MySQL 5.5.30 to MySQL 5.6.10, both with default settings using only the InnoDB storage engine.  In my testing I discovered that innodb_old_blocks_time had an effect on performance of the benchmark.  There was […]

Concatenating MyISAM files

Recently, I found myself involved in the migration of a large read-only InnoDB database to MyISAM (eventually packed). The only issue was that for one of the table, we were talking of 5 TB of data, 23B rows. Not small… I calculated that with something like insert into MyISAM_table… select * from Innodb_table… would take […]

How FLUSH TABLES WITH READ LOCK works with Innodb Tables

Many backup tools including Percona Xtrabackup, MyLVMBackup and others use FLUSH TABLES WITH READ LOCK to temporary make MySQL read only. In many cases the period for which server has to be made read only is very short, just few seconds, yet the impact of FLUSH TABLES WITH READ LOCK can be quite large because […]

What does Handler_read_rnd mean?

MySQL’s SHOW STATUS command has two counters that are often confusing and result in “what does that mean?” questions: Handler_read_rnd Handler_read_rnd_next As I understand it, there is some historical context to the choice of names here, hearkening back to before I was involved with MySQL, way back when it was a wrapper around ISAM tables […]

How fast is FLUSH TABLES WITH READ LOCK?

A week or so ago at the MySQL conference, I visited one of the backup vendors in the Expo Hall. I started to chat with them about their MySQL backup product. One of the representatives told me that their backup product uses FLUSH TABLES WITH READ LOCK, which he admitted takes a global lock on […]

Air traffic queries in MyISAM and Tokutek (TokuDB)

This is next post in series Analyzing air traffic performance with InfoBright and MonetDB Air traffic queries in LucidDB Air traffic queries in InfiniDB: early alpha Let me explain the reason of choosing these engines. After initial three posts I am often asked “What is baseline ? Can we compare results with standard MySQL engines […]

Should you move from MyISAM to Innodb ?

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 […]

Using Multiple Key Caches for MyISAM Scalability

I have written before – MyISAM Does Not Scale, or it does quite well – two main things stopping you is table locks and global mutex on the KeyCache. Table Locks are not the issue for Read Only workload and write intensive workloads can be dealt with by using with many tables but Key Cache […]

ANALYZE: MyISAM vs Innodb

Following up on my Previous Post I decided to do little test to see how accurate stats we can get for for Index Stats created by ANALYZE TABLE for MyISAM and Innodb. But before we go into that I wanted to highlight about using ANALYZE TABLE in production as some people seems to be thinking […]

Beware of MyISAM Key Cache mutex contention

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 […]