…MySQL Conference & Expo 2013 the week before last,…corrupt data pt-heartbeat –utc –check always returns 0 pt-query-digest 2.2 … prints the wrong variable name in verbose mode when –function is used And more The …need to specify cluster node DSNs in a DSN table (–recursion-method=dsn). See https://…
Post: Percona Toolkit 2.2.2 released; bug fixes include pt-heartbeat & pt-archiver
May 6, 2013 By 2 Comments
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
…rows which are found and returned up to the top level MySQL part for processing …tables but because the access type to the tables is “const” MySQL does not count it as access to two tables. In… aggregate functions are removed (A) – look at number of rows examined divided by number of tables in join (…
Post: Upgrading MySQL
January 5, 2010 By 24 Comments
…. For example you may get queries returning different result or getting different execution plan…you’re running application which uses simple MySQL functionality which is unlikely to be affected. …table-checksum to ensure data is the same. It is possible some update statements worked differently in…
Post: Statement based replication with Stored Functions, Triggers and Events
December 16, 2011 By 4 Comments
… will stop with an error. Example: mysql> CREATE FUNCTION this_year() RETURNS INT DETERMINISTIC RETURN YEAR(CURDATE()); mysql> insert into t VALUES(this_year()); Binary… to our tables the queries inside the procedure get logged and not the call to the procedure itself. So in this case…
Post: Stored Function to generate Sequences
April 2, 2008 By 17 Comments
… it is not as safe as if you use Innodb table in this case. Even though implementation is just 2 lines of…. This way of using this function allows you to “inject” the value to be returned next time this function is called. Sometimes people wonder why you would like to use sequences instead of MySQL auto…
Post: Memory allocation in Stored Function
August 26, 2007 By 8 Comments
… to look deeply – let’s try simple table (experiments with MySQL 5.0.45) CREATE TABLE `testf` ( `id` int(11) NOT NULL auto…=latin1 mysql> select count(*) from testf; +———-+ | count(*) | +———-+ | 20971520 | +———-+ 1 row in set (0.00 sec) and simple function I’ve found in MySQL manual: CREATE FUNCTION hello (s CHAR(20)) RETURNS CHAR(50) RETURN CONCAT(‘Hello…
Post: Testing MySQL column stores
August 16, 2010 By 15 Comments
…in the most recent software release. An example of such a problem would be “select avg(char_column) from table…MySQL aggregation functions. Notably, GROUP_CONCAT is not supported, which is something I hope they rectify in a future version. In… GROUP BY queries returned unexpected results as well…
Post: MySQL opening .frm even when table is in table definition cache
November 21, 2011 By 8 Comments
… the above strace shows. In MySQL 5.5 you can find in sql/datadict.cc a function named dd_frm_type(). In MySQL 5.1, for some reason yet unknown to humans, it lives in… generic table type (I think, I haven’t gone back into the deep history of the FRM file format to confirm) return…
Post: The Optimization That (Often) Isn't: Index Merge Intersection
December 14, 2012 By 6 Comments
…version 5.0, MySQL could only use one index per table in a given query without any exceptions; folks… MySQL is using three different indexes to search approximately 8100 out of 4.5M rows to return the… A new version of MySQL is released that has some new optimizer functionality that you end up missing…
Post: Announcing Percona Server 5.5.25a-27.1
July 21, 2012 By Leave a Comment
…() function will always return NULL. The LOAD DATA INFILE and SELECT INTO OUTFILE statements will fail with the following error: “The MySQL server… count in statistics tables in Percona Server 5.5.24-26.0. Bug fixed #1008278 (Vladislav Lesin). PAM authentication plugin was in different directories in…
