June 19, 2013

Post: pt-online-schema-change and default values

June 21, 2012 By 1 Comment

…in MySQL I can ignore default value and it will be assigned based on the column…in cleanup) Error copying rows from `sbtest`.`sbtest` to `sbtest`.`_sbtest_new`: Copying rows caused a MySQL…

Filed Under: Insight for DBAs, MySQL

Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5

April 4, 2012 By 4 Comments

… post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL… created, rows from table t2 are read and hash function is applied to the columns participating in the… that the IO access pattern has been changed to become sequential. The two other most important…

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

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… column named “value”. OK, sounds easy enough: mysql: SHOW CREATE TABLE innodb_myisam_stopword\G *************************** 1. row …we change the above query to be “+james +peterson arizona” then we might expect to get…

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

Post: Data compression in InnoDB for text and blob fields

May 30, 2012 By 2 Comments

…to compress only certain types of columns in a table while leaving other columns…MySQL 5.5) you can now leverage table compression by specifying ROW_FORMAT=COMPRESSED.  In our case we only wanted MySQL to try to…

Filed Under: Insight for DBAs, Insight for Developers, MySQL, Percona Software

Post: Dynamic row format for MEMORY tables

September 6, 2011 By 5 Comments

…in MySQL in 2008): The key columns must come before any non-key variable-length columns. For performance reasons, the key columns are stored in…row. If there were any variable-length column in between them, it had to be stored in…

Filed Under: MySQL, Percona Software

Post: MySQL Indexing Best Practices: Webinar Questions Followup

August 16, 2012 By 4 Comments

…you need to consider is string comparison in MySQL is…to differ only by first column. Regarding changing primary key to include such column…to Table1 to lookup row by primary key when you do not need an index on a field which is used to join tables in… column. In such cases it indeed might be better to…

Filed Under: Insight for DBAs, MySQL

Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact

March 12, 2012 By 12 Comments

I have been working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer enhancements one by one. So in… new optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…

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

Post: Ultimate MySQL variable and status reference list

January 8, 2011 By 4 Comments

…to the amazing MySQL manual, especially the option and variable reference table. But just as frequently, I want to…column…change…

Filed Under: Insight for DBAs, MySQL

Post: Using UNION to implement loose index scan in MySQL

August 10, 2006 By 15 Comments

…in this case we only can give a hand to MySQL Optimizer and change the query so it can handle it well…. use UNION: mysql…column in…

Filed Under: Insight for Developers Tagged With: ,

Post: Trailing spaces in MySQL

November 27, 2006 By 7 Comments

… was easy in MySQL. Both CHAR and VARCHAR types meant the same, only being difference in the sense of fixed or dynamic row length… MySQL 5.0 however things changed so now VARCHAR keeps trailing spaces while CHAR columns do not any more. Well in reality CHAR columns are padded to full…

Filed Under: Insight for Developers Tagged With:
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