…in MySQL >= 5.5.23 work, I would like to mention quickly, that how drop table in MySQL…number of pages in…function meaning that only the entries in the flush_list should be removed. Following are the steps performed in this function…
Post: DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
… means MySQL can employ many other optimizations like for …in both MySQL 5.6 and MariaDB 5.5. You can read more about BKA in MySQL 5.6 here and BKA in…rows from table t2 are read and hash function is applied to the columns participating in…number in MariaDB 5.5 that is quite large as compared to 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…
Post: Impact of the sort buffer size in MySQL
October 25, 2010 By 8 Comments
…I could have used the uuid() function of MySQL. For the benchmark, I used an…limit 78000,1;show session status like ‘Sort_merge_passes’;select * from sorttest… $TIME” done which in addition to output the total time, output the number of Sort_… be a pretty high overhead per row (~37 bytes) but if the …
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…functions like NOW(). In…number of lines in the order_lines table, three orders of magnitude more quickly than COUNT(*). mysql…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
… callback function to handle the output of each input asynchronously, if you like. Right … run by the native database interface (MySQL): mysql> select word, md5(word), md5(reverse(word…row in set (0.00 sec) How to factor numbers create table dataset ( id bigint auto_increment primary key, prime_number…
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
…number of rows estimated from each row in a join and multiply them to see how many rows will be examined in…rows/sec. No info about functions cost Since MySQL 5.0 you may use user functions in…
Post: A rule of thumb for choosing column order in indexes
June 5, 2009 By 15 Comments
… to decide which columns should come first in an index. This is not specific to MySQL, it’s generally applicable to any… simplicity. Let’s start with this query, which returns zero rows but does a full table scan. EXPLAIN says there are…
Post: Using flow control functions for performance monitoring queries
May 24, 2008 By 12 Comments
I’m not big fan on flow control functions like IF or CASE used in MySQL Queries as they are often abused used to….0017 | +———+——————+——–+——–+——–+ 1 row in set (7.51 sec) This query scans through page generation log for some site and reports number of requests…
Post: MySQL extensions for hosting
April 24, 2008 By 11 Comments
… to isolate some functionalities from Mark Callaghan’s MySQL patch bundle. They…. Monitoring those numbers every minute can show you changes in usage by…rows in set (0.00 sec) mysql> SHOW INDEX_STATISTICS LIKE ‘hosting2%’; +——————————————–+———–+ | Index | Rows…
