…MySQL…Handler_prepareblogpercona.commanual Handler_read_firstblogpercona.commanual Handler_read_keyblogpercona.commanual Handler_read_lastblogpercona.commanual Handler_read_nextblogpercona.commanual Handler_read_prevblogpercona.commanual Handler_read_rndblogpercona.commanual Handler_read…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…/A N/A 1 0 Handler_read_key 508833 623738 622184 508913 507516 Handler_read_next 574320 574320 572889 574320 572889 Handler_read_rnd_next 136077 136094… the status counter Innodb_rows_read. While MySQL 5.6 is also reporting increased numbers for the counter Handler_read_key. This is because of… the value for counter Handler_read_key is more or less the same for MariaDB 5.5 when compared to MySQL 5.5, and…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
… MySQL 5.6. Next interesting thing are the last two columns of the table above and the values for ‘Handler_read_key‘, ‘Handler_read_next’ and ‘Handler_read_rnd_next’. MariaDB 5.5 with Hash Joins enabled is doing less Handler reads as compared to…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a… optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take… for filtering records. For example, suppose you have a key defined as: KEY `i_l_partkey` (`l_partkey`,`l_quantity`,`l_shipmode…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
…) mysql> show status like “Handler%”; +—————————-+——-+ | Variable_name | Value | +—————————-+——-+ | Handler_commit | 0 | | Handler_delete | 0 | | Handler_discover | 0 | | Handler_prepare | 0 | | Handler_read_first | 0 | | Handler_read_key | 1 | | Handler…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
… 62742394, 62742398, 62742402, 62743720, 62743962, 62744142, 62744144, 62744146) With secondary key defined on (group_id,deleted) This pattern of medium …row_sel_get_clust_rec_for_mysql,row_search_for_mysql,ha_innobase::index_read,handler::read_ra nge_first,handler::read_multi_range_next,QUICK_RANGE…
Post: What does Handler_read_rnd mean?
June 15, 2010 By 15 Comments
MySQL‘s SHOW STATUS command has two counters that are often confusing and result in “what does that mean?” questions: Handler_read_rnd Handler_read… InnoDB, it means to read a row based on a primary key value. Handler_read_rnd_next is incremented when handler::rnd_next() is called. This is basically a cursor operation: read the “next…
Post: MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown
March 14, 2013 By 2 Comments
…: SIMPLE table: cast_info type: ref possible_keys: role_id_note key: role_id_note key_len: 4 ref: const rows: 10259274 Extra… at handler level. Condition pushdown is one of the new features of MySQL 5.6, and actually is a great improvement over MySQL 5.5. For example, in this case, the actual number of “Handler_read…
Post: Wow. My 6 year old MySQL Bug is finally fixed in MySQL 5.6
August 30, 2012 By 2 Comments
…Handler_read_next | 1305742982 | mysql> select count(*) from trunc where i=4147483647; +———-+ | count(*) | +———-+ | 0 | +———-+ 1 row in set, 1 warning (0.04 sec) | Handler_read…
Post: Joining on range? Wrong!
May 17, 2010 By 10 Comments
… beginning of MySQL, however unless you…Handler_read%’; +———————–+——–+ | Variable_name | Value | +———————–+——–+ | Handler_read_first | 0 | | Handler_read_key | 3 | | Handler_read_next | 118181 | | Handler_read_prev | 0 | | Handler_read_rnd | 0 | | Handler_read…
