…KEY (id) ) CREATE INDEX…in the main table. and transactions for this workload are: $ID=monotonically increasing…how…to run: sysbench –test=insert_roll.lua –oltp-table-size=10000 –mysql-user=root –oltp-tables-count=32 –mysql…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
…keys: d key: d key_len: 7 ref: NULL rows: 3681 Extra: Using where 1 row in set (0.01 sec) mysql…how it is. I also tried to increase cardinality by having all rows to…
Post: Using UNION to implement loose index scan in MySQL
August 10, 2006 By 15 Comments
… row in set (0.01 sec) As you see instead only first index keypart is used (key_len is… to 3, whle “key_len” remains the same. This however looks like a bug in the MySQL …increased to 8. Lets see how query times differ in these cases: mysql> SELECT sql_no_cache name FROM people WHERE age=19 AND zip IN…
Post: Getting MySQL to use full key length
January 31, 2007 By 5 Comments
…increase selectivity it anyway does not cost much more as basically the same data is traversed anyway. So how do you force MySQL…keys: group_id key: group_id key_len: 12 ref: NULL rows: 51 Extra: Using where 1 row in…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…increased numbers for the counter Handler_read_key. This is because of how status counter values are incremented when index…to MySQL 5.5, and this does not make sense to me. Probably its due to a bug in how…Bad Plan id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE …
Post: When EXPLAIN estimates can go wrong!
October 13, 2011 By 7 Comments
…keys: type_created key: type_created key_len: 1 ref: const rows: 185440 Extra: Using index On 5.5: mysql […in MySQL 5.1 and how it calculates the row estimates. This bug was tracked down to http://bugs.mysql…to increase the quality of the estimation, and make the estimation very precise if the index…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… STATUS output and how to use this info to improve MySQL Performance. To start with …KEY (`parent_id`) REFERENCES `parent` (`id`) ON DELETE CASCADE Trying to add in child table, in index `par_ind` tuple: DATA TUPLE: 2 fields; 0: len…size being unflushed you may want to increase it. You also can see …
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
…keys | key | key_len | ref | rows | filtered | Extra | +—-+————-+———-+——-+—————+—————+———+————————-+——-+———-+————-+ | 1 | SIMPLE | supplier | index | PRIMARY | i_s_nationkey | 5 | NULL | 20174 | 100.00 | Using index…
