… take on server. There is no comparable variables of how many user variables are allocated (and how much …to see how much memory is being used by current MEMORY tables: mysql> select sum(data_length+index_length) … I would say these are rather rare in MySQL. Most suspected memory leaks end up being …
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… 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… aimed at. Index Condition Pushdown Traditional B-Tree index lookups have some limitations in cases such as range scans, where index parts after the…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
…in both MySQL 5.6 and MariaDB 5.5. You can read more about BKA in MySQL 5.6 here and BKA in…much of a difference here. Now let’s take a look at the status counters. Counter Name MySQL 5.5 MySQL 5.6 MySQL…
Post: Using UNION to implement loose index scan in MySQL
August 10, 2006 By 15 Comments
…MySQL Indexing, however very important for successfull MySQL Performance Optimization is understanding when exactly MySQL is going to use index and how…in set (0.09 sec) Ethen though this query looks much more complicated MySQL is able to execute it much…if it would take some 100 queries in the union …
Post: How much space does empty Innodb table take ?
December 16, 2008 By 7 Comments
How much space would empty MyISAM table take ? Probably 8K for .frm file, 1KB for .MYI file and …. .MYI file can be larger if you have many indexes. How much space will Innodb take: mysql> create table test_innodb(a int, b int… small tables are used The information in INFORMATION_SCHEMA can’t be used to judge how much space table is really taking on disk.
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… you understand how much having data in memory changed things here is small example with numbers. If you have your data fully in memory… show benefit from using indexes. In fact even MySQL optimizer currently does not take it into account. For In memory workload index accesses might be faster…
Post: Working with large data sets in MySQL
July 5, 2007 By 12 Comments
…in MySQL is patience and careful planning. Both of which relate two single property of large data sets – it can take…plan carefully how you’re going to alter your database because it takes a…much can use trial and error approach even for production – found some bad queries fixed them by adding indexes…
Post: How much memory Innodb locks really take ?
July 13, 2006 By 11 Comments
…61 Data_length: 100253696 Max_data_length: 0 Index_length: 128974848 Data_free: 0 Auto_increment:…Now lets see how much exclusinve locks take: mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> select count…how much memory is using locking all the rows – so all rows are locked from the page. In…
Post: How much memory Innodb Dictionary can take ?
May 6, 2010 By 3 Comments
…restrict that limit. So how much memory can it really take ? Here is some production stats from real system: mysql> select count(*) from … in set (8.04 sec) mysql> select count(*) from INNODB_SYS_INDEXES; +———-+ | count(*) | +———-+ | 451773 | +———-+ 1 row in set (2.75 sec) In this …
Post: Explaining Indexes with a Library Metaphor
August 30, 2011 By 1 Comment
… back the description of the shelf and row in which these books can be found. You then…step would be much faster. Using an index with range scans You would like to count how many books…how many pages it has. Conclusion If you imagine yourself doing these tasks, you can imagine how long they might take…
