…index can be used to satisfy order by, index however will not be helpful to check c=5 (unless it is index covered query). Index… – expressions or functions will block index usage for order by. Sort by …indexed) Force index if needed In some cases MySQL Optimizer may prefer to use different index…
Post: Dynamic row format for MEMORY tables
September 6, 2011 By 5 Comments
…engine (also known as HEAP) in MySQL has been one of the … space (VARCHAR) or outright impossible (BLOB). Indexes on BLOB columns are not supported….work to remove them. The full usage notes, including discussion when the …application-specific tests. We start by checking if there is any performance …
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…: 56 Rows_examined: 1113 LOGGING OF THE REPLICATED STATEMENTS Normally MySQL will not write into slow log any queries executed by…. Full_join means any of the joins didn’t use indexes. If a temporary table is required for query execution Tmp… was done through temporary files. INNODB USAGE The final part are the InnoDB usage statistics. MySQL currently allows you to see many per…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…There will be another blog post about the usage and performance of the splitter. It is…42GB (with indexes) # du -sh * 203M ibdata1 128M ib_logfile0 128M ib_logfile1 988K mysql 2.1G …Index_length: 539279360 Data_free: 4194304 Auto_increment: NULL Create_time: 2011-05-10 04:26:14 Update_time: NULL Check…
Post: Living with backups
November 6, 2008 By 28 Comments
…tables which have dedicated buffers only to store indexes, while the actual data is always read from …-tools/tar … Please cosult ionice man page for usage details, it’s really very simple to … { last; } sleep(1); } What this script does is to check MySQL status every second and in case the number…
Post: MySQL Consulting - Being on your own
February 20, 2007 By 7 Comments
…MySQL I actually talk to MySQL Professional Services Director – Josh, to check if I should move to the role of MySQL… to have mini training done about efficient MySQL usage, or simply when security is too tight … may be as simple as adding few indexes and tuning MySQL Server settings. It is more the …
Comment: COUNT(*) vs COUNT(col)
April 25, 2007 By 45 Comments
… Database pages 18664 Modified db pages 0 restart mysql and check the count of (rajid): mysql> select count(rajid) from wp_comments; +————–+ | count… reads the index data, not the row data for the table when you use a secondary index. Check the buffer pool usage: Total memory…
Post: Moving from MyISAM to Innodb or XtraDB. Basics
November 22, 2010 By 2 Comments
…table lock behavior in your applications, also check if your application handled deadlocks well. MyISAM…while as depending on the schema and usage Innodb tables may increase in size …index scan for Innodb. Defaults You need to know two things about defaults for Innodb. First Depending on MySQL…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… index read mysql tables in use 1, locked 1 LOCK WAIT 3 lock struct(s), heap size 320 MySQL … 1000 This section shows Buffer pool activity and memory usage. You can see total memory allocated by Innodb (… allocated in additional memory pool (so you can check if it is sized right), total number of …
Post: Choosing innodb_buffer_pool_size
November 3, 2007 By 39 Comments
… data pages – it also contain adaptive hash indexes, insert buffer, locks which also take some time…It is usually much better to simply check it. Start MySQL With 10GB Innodb buffer pool for …MySQL in memory by using –memlock – just be careful as in case you have memory usage spike you may have MySQL…
