… is further extended to improve join performance. As I told you above, when table t1 would be joined to table t2, then selected rows from… before MySQL has only supported one join algorithm and that is Nested Loop Join. MariaDB has introduced a new join algorithm Hash Join. This join algorithm…
Post: Joining many tables in MySQL - optimizer_search_depth
April 20, 2012 By 6 Comments
… EXPLAIN phase yet making it unusable to check the optimizer performance. Solution for this problem was to use set optimizer_search… explanation somewhat conflicting though as if we assume MySQL users do not join lots of tables (less than 7) when using 0 as… than backward compatibility. In MySQL 5.6 things are likely to get even better handling joins of many tables as optimizer heuristics are…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…performing the benchmark on IO bound workload, mentioned above. Counter Name MySQL 5.5 MySQL 5.6 MySQL…MRR range scans had to be performed. As in the table above you can with default …performance of secondary key lookups as well. But this works only with joins and specifically with Block Access Join…
Post: MariaDB 5.3 is released as GA!
March 5, 2012 By 17 Comments
… MariaDB as a first-class member of the MySQL family of databases. Finally, High Performance MySQL, Third Edition mentions MariaDB in many places… binary log enabled Faster queries through speedier joins, faster subqueries, and elimination of useless tables in joins Thread pooling and a segmented key…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… and delivers great performance. What could be the reason ? The reason is normally table design and understanding inner works of MySQL. If you… 1% or rows or less full table scan may be faster. Avoid joins to large tables Joining of large data sets using nested loops is very expensive. Try to avoid it. Joins to smaller tables is…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 27 Comments
…small benchmark which shows MySQL performance when you use 3 different approaches: ENUM, VARCHAR and tinyint (+joined table) columns. In practice you… close performance, while join performance degraded dramatically. Here is why: mysql> explain select SQL_NO_CACHE c.city from cities_join c JOIN states…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 12 Comments
…table_name: orders mview_table_schema: demo mview_table_alias: o mview_join_condition: NULL mview_join_order: 999 *************************** 2. row *************************** mview_table…performance…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…Performance_schema_rwlock_classes_lostblogpercona.commanual Performance_schema_rwlock_instances_lostblogpercona.commanual Performance_schema_table_handles_lostblogpercona.commanual Performance_schema_table_instances_lostblogpercona.commanual Performance…
Post: MySQL VIEW as performance troublemaker
August 12, 2007 By 53 Comments
… as with subqueries and derived tables MySQL 5.0 will fail and perform very inefficiently in many counts. MySQL has two ways of handling… “join cache” is used to perform it relatively efficient, however for large derived tables it will become nightmare. So be very careful implementing MySQL…
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
… In MySQL 5.0 with addition of greedy join the problem on looking at too many table join combinations in joins with very large tables is…. The other reason for difference is join_buffer which reduces number of passes MySQL had to perform and so number of row combinations… which stage MySQL actually perform the sort or creates temporary table and so how much rows will be stored to temporary table. Sometimes it…
