June 18, 2013

Post: Replication in MySQL 5.6: GTIDs benefits and limitations - Part 2

May 30, 2013 By 6 Comments

… on MySQL 5.6 GTIDs. You can find part one here. Our goal will be to go from setup #1 to setup #2…=10002; mysql> start slave; # And then check the number of records from the t table s1> select count(*) from t; +———-+ | count(*) | +———-+ | 2… fixed, it is good to be aware of the current limitations.

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

Post: MySQL and the SSB - Part 2 - MyISAM vs InnoDB low concurrency

May 22, 2013 By Leave a Comment

…part two in what is now a continuing series on the Star Schema Benchmark. In my previous blog post I compared MySQL… another advantage of InnoDB. SSB Flight #2 Flight #2 is similar to Flight #1. MyISAM … good for raw performance, but there are limitations which MyISAM imposes that are difficult to …

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Post: Replication in MySQL 5.6: GTIDs benefits and limitations - Part 1

May 21, 2013 By 8 Comments

…specific replication topology. However you should keep in mind some limitations of the current implementation. This post is the first …field, Auto_Position: # Slave #1 mysql> show slave status\G [...] Auto_Position: 1 -> GTID-based positioning # Slave #2 mysql> show slave status\G [...] Auto_Position…

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Post: Understanding the maximum number of columns in a MySQL table

April 8, 2013 By 5 Comments

… those using MySQL, Percona Server, MariaDB or any other of the MySQL branches/forks, you get to have these odd limitations. Why do… UI for generating reports. This evolved into the SQL based MySQL, with MySQL 1.0 being released in 1995. The FoRM file…); } Which is, of course, obvious! Various parts of this limit are: info_length is roughly 2+strlen(field_name) for each field. Unless…

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Post: trx descriptors: MySQL performance improvements in Percona Server 5.5.30-30.2

April 12, 2013 By 3 Comments

… view creation. It was originally reported as a part of MySQL bug #49169 and can be described as …Percona Server as of version 5.5.30-30.2 significantly reduces the impact of the list scan… optimization in MySQL 5.6 to achieve even better scalability while removing the read-only limitations. Let’s …

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Post: The write cache: Swap insanity tome III

April 19, 2013 By 5 Comments

…sysctl -p” and we are done. Swappiness solves part of the swapping issue but not all… interleave the allocation of memory for the MySQL process using the numactl utility, drop …about 28GB and the file upload size limit is 5GB. So, about 28GB was … 0 49664 2532 164356 30539 21120 2 3 81 13 0 Note the …

Filed Under: Hardware and Storage, Insight for DBAs, MySQL Tagged With: , , ,

Post: MySQL Limitations Part 4: One thread per connection

October 27, 2010 By 14 Comments

… on what’s seriously limiting MySQL in core use cases (links: part 1, 2, 3). This post is about the way MySQL handles connections, allocating one thread per connection to the server. MySQL is… them. That’s why I listed those as major limitations. And because MySQL is a multi-threaded database for Web usage that…

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Post: MySQL Limitations Part 2: The Binary Log

October 23, 2010 By 11 Comments

… a series on what’s seriously limiting MySQL in certain circumstances (links: part 1). In the first part, I wrote about single-threaded replication… data in the server. The binary log is a real limitation in MySQL. The binary log is necessary not only for replication… transaction logs, so there’s even precedent for this among MySQL storage engines. And there is Galera’s multi-master synchronization…

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Post: MySQL Limitations Part 3: Subqueries

October 25, 2010 By 21 Comments

… third in a series on what’s seriously limiting MySQL in certain circumstances (links: part 1, 2). This post is about subqueries, which in…, followed by N queries to table b. This is because MySQL rewrites the query to make the inner query dependent on…. And many MySQL users have learned to simply write JOINs instead, so it isn’t that much of a limitation. But it…

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Post: InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

…in MySQL 5.6: Part 2, The Queries![/caption] This is part 2 in a 3 part series. In part 1… dir_test_myisam ORDER BY 3 DESC LIMIT 5; +——–+——————————+——————–+ | id | full_name | score | +——–+——————————+——————–+ | 74717 | James …

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