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Benchmarking Percona Server TokuDB vs InnoDB

May 7, 2013 By Vadim Tkachenko 29 Comments

After compiling Percona Server with TokuDB, of course I wanted to compare InnoDB performance vs TokuDB. I have a particular workload I’m interested in testing – it is an insert-intensive workload (which is TokuDB’s strong suit) with some roll-up aggregation, which should produce updates in-place (I will use INSERT .. ON DUPLICATE KEY UPDATE statements [...]

Filed Under: Benchmarks, MySQL, Percona Server Tagged With: Benchmarking, InnoDB, Percona Server, TokuDB

InnoDB Full-text Search in MySQL 5.6 (part 1)

February 26, 2013 By Ernie Souhrada 1 Comment

I’ve never been a very big fan of MyISAM; I would argue that in most situations, any possible advantages to using MyISAM are far outweighed by the potential disadvantages and the strengths of InnoDB. However, up until MySQL 5.6, MyISAM was the only storage engine with support for full-text search (FTS). And I’ve encountered many [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: Ernie Souhrada, FTS, FullText Search, InnoDB, MyISAM, MySQL 5.6

Concatenating MyISAM files

November 19, 2012 By Yves Trudeau 5 Comments

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 [...]

Filed Under: MySQL

Full Text Search Webinar Questions Followup

August 24, 2012 By Bill Karwin 5 Comments

I presented a webinar this week to give an overview of several Full Text Search solutions and compare their performance. Even if you missed the webinar, you can register for it, and you’ll be emailed a link to the recording. During my webinar, a number of attendees asked some good questions. Here are their questions and my [...]

Filed Under: Events and Announcements, Insight for Developers, MySQL

MySQL Indexing Best Practices: Webinar Questions Followup

August 16, 2012 By Peter Zaitsev 4 Comments

I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others are better answered in writing anyway. Q: One developer on our team wants to replace longish (25-30) indexed varchars with [...]

Filed Under: Insight for DBAs, MySQL

Innodb Table Locks

July 31, 2012 By Peter Zaitsev 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:

---TRANSACTION 12303, ACTIVE 26 sec
mysql tables in use 2, locked 0
MySQL thread id 53038, OS thread handle 0x7ff759b22700, query id 3918786 localhost root Sending data
select count(*) from sbtest,sbtest x
Trx read view will not see trx with id >= 12304, sees < 12301

---TRANSACTION 12303, ACTIVE 26 sec

mysql tables in use 2, locked 0

MySQL thread id 53038, OS thread handle 0x7ff759b22700, query id 3918786 localhost root Sending data

select count(*) from sbtest,sbtest x

Trx read view will not see trx with id >= 12304, sees < 12301

As you can [...]

Filed Under: Insight for DBAs, MySQL

Dynamic row format for MEMORY tables

September 6, 2011 By Laurynas Biveinis 5 Comments

The latest Percona Server release has one new feature: now MEMORY tables can have BLOB and TEXT columns, and VARCHAR columns will not waste space due to implicit extension to CHAR.

Filed Under: MySQL, Percona Software

Moving from MyISAM to Innodb or XtraDB. Basics

November 22, 2010 By Peter Zaitsev 2 Comments

I do not know if it is because we’re hosting a free webinar on migrating MyISAM to Innodb or some other reason but recently I see a lot of questions about migration from MyISAM to Innodb. Webinar will cover the process in a lot more details though I would like to go over basics in [...]

Filed Under: Events and Announcements, MySQL Tagged With: InnoDB, MyISAM, XtraDB

How many partitions can you have ?

December 5, 2009 By Peter Zaitsev 19 Comments

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 [...]

Filed Under: Benchmarks, Insight for DBAs, MySQL Tagged With: Bugs, InnoDB, MyISAM

How (not) to find unused indexes

October 16, 2009 By Morgan Tocker 2 Comments

I’ve seen a few people link to an INFORMATION_SCHEMA query to be able to find any indexes that have low cardinality, in an effort to find out what indexes should be removed.Â This method is flawed – here’s the first reason why:

CREATE TABLE `sales` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`customer_id` int(11) DEFAULT NULL,
`status` enum('archived','active') DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `status` (`status`)
) ENGINE=MyISAM AUTO_INCREMENT=65691 DEFAULT CHARSET=latin1;
mysql> SELECT count(*), status FROM sales GROUP by status;
+----------+---------+
| count(*) | statusÂ  |
+----------+---------+
|Â Â Â  65536 | archived |
|Â Â Â Â Â  154 | activeÂ  |
+----------+---------+
2 rows in set (0.17 sec)
mysql> EXPLAIN SELECT * FROM sales WHERE status='active'; # query 1
+----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+
| id | select_type | table | type | possible_keys | keyÂ Â Â  | key_len | refÂ Â  | rows | ExtraÂ Â Â Â Â Â  |
+----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+
|Â  1 | SIMPLEÂ Â Â Â Â  | sales | refÂ  | statusÂ Â Â Â Â Â Â  | status | 2Â Â Â Â Â Â  | const |Â  196 | Using where |
+----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+
1 row in set (0.06 sec)
mysql> EXPLAIN SELECT * FROM sales WHERE status='archived'; # query 2
+----+-------------+-------+------+---------------+------+---------+------+-------+-------------+
| id | select_type | table | type | possible_keys | keyÂ  | key_len | refÂ  | rowsÂ  | ExtraÂ Â Â Â Â Â  |
+----+-------------+-------+------+---------------+------+---------+------+-------+-------------+
|Â  1 | SIMPLEÂ Â Â Â Â  | sales | ALLÂ  | statusÂ Â Â Â Â Â Â  | NULL | NULLÂ Â Â  | NULL | 65690 | Using where |
+----+-------------+-------+------+---------------+------+---------+------+-------+-------------+
1 row in set (0.01 sec)

CREATE TABLE `sales` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`customer_id` int(11) DEFAULT NULL,

`status` enum('archived','active') DEFAULT NULL,

PRIMARY KEY (`id`),

KEY `status` (`status`)

) ENGINE=MyISAM AUTO_INCREMENT=65691 DEFAULT CHARSET=latin1;

mysql> SELECT count(*), status FROM sales GROUP by status;

+----------+---------+

| count(*) | statusÂ |

+----------+---------+

|Â Â Â 65536 | archived |

|Â Â Â Â Â 154 | activeÂ |

+----------+---------+

2 rows in set (0.17 sec)

mysql> EXPLAIN SELECT * FROM sales WHERE status='active'; # query 1

+----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+

+----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+

+----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+

1 row in set (0.06 sec)

mysql> EXPLAIN SELECT * FROM sales WHERE status='archived'; # query 2

+----+-------------+-------+------+---------------+------+---------+------+-------+-------------+

+----+-------------+-------+------+---------------+------+---------+------+-------+-------------+

+----+-------------+-------+------+---------------+------+---------+------+-------+-------------+

1 row in set (0.01 sec)

The cardinality of status index is woeful, but provided that the application [...]

Filed Under: Insight for DBAs, MySQL Tagged With: explain, indexing, MySQL, Tips

Benchmarking Percona Server TokuDB vs InnoDB

InnoDB Full-text Search in MySQL 5.6 (part 1)

Concatenating MyISAM files

Full Text Search Webinar Questions Followup

MySQL Indexing Best Practices: Webinar Questions Followup

Innodb Table Locks

Dynamic row format for MEMORY tables

Moving from MyISAM to Innodb or XtraDB. Basics

How many partitions can you have ?

How (not) to find unused indexes

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