June 19, 2013

Comment: Duplicate indexes and redundant indexes

information_schema.table_constraints a INNER JOIN information_schema.key_column_usage b ON a.constraint_name = b.constraint_name AND a.table_schema = b.table_schema AND a.table

Post: Find unused indexes

… some tables to Information Schema with useful information to understand the server activity and identify the source of the load. Those tables store …DROP KEY `fkey_order_line_2`; — type:non-unique ALTER TABLE `tpcc`.`orders` DROP KEY `idx_orders`; — type:non-unique ALTER TABLE `tpcc`.`stock` DROP

Post: How Percona does a MySQL Performance Audit

… heavily loaded, I may even do some INFORMATION_SCHEMA queries to help me find the biggest tables and so forth. If the server is heavily loaded or has a lot of data, touching the INFORMATION_SCHEMA can… that there are InnoDB tables whose .frm files exist but have been dropped from InnoDB, for example. (The INFORMATION_SCHEMA query will surely trigger…

Post: InnoDB Full-text Search in MySQL 5.6 (part 1)

… adding and dropping FT indexes, it’s entirely possible to DROP multiple FT indexes with InnoDB in the same ALTER TABLE statement, but… innodb_ft_aux_table=’test/dir_test_innodb’; mysql> set global innodb_optimize_fulltext_only=1; mysql> select * from information_schema.innodb_ft… | +———————-+———-+———-+———-+ 1 row in set (4.60 sec) mysql> select * from information_schema.innodb_ft_config; +—————————+———+ | KEY | VALUE | +—————————+———+ | optimize_checkpoint_limit | 180 | | synced…

Post: Shard-Query EC2 images available

… InnoDB schema from one shard. The schema is duplicated 20 times (but not the ontime_fact data): DROP TABLE IF EXISTS `dim_airport`; CREATE TABLE…` (`DayOfWeek`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 COMMENT=’Contains the date information from the BTS ontime flight data. Note dates may not…

Post: Connecting orphaned .ibd files

information_scheme database in Percona Server though). The structure of these tables is following: SYS_TABLES: CREATE TABLE `SYS_TABLEStable test/t2 In this case you need to drop table

Post: MySQL 5.5 and MySQL 5.6 default variable values differences

… | 5 | | PERFORMANCE_SCHEMA_EVENTS_WAITS_HISTORY_LONG_SIZE | 10000 | 100 | | PERFORMANCE_SCHEMA_MAX_RWLOCK_INSTANCES | 1000000 | 1724 | | PERFORMANCE_SCHEMA_MAX_TABLE_HANDLES | 100000 | 2223… 200 tables in this system. innodb_stats_on_metadata is disabled by default in MySQL 5.6 Welcome to much faster information_schema… when you have large number of tables or if you do many create/drop of innodb tables. optimizer_switch is the catch all…

Post: Side load may massively impact your MySQL Performance

… you get it right. Performance of sysbench OLTP on small table drops more than 150 times when heavy mysqldump is running concurrently… at the buffer pool contents. mysql [localhost] {msandbox} (information_schema) > select concat_ws(‘.’, t.schema, t.name, i.name) as index_name, sum…

Post: Announcing Percona Server for MySQL version 5.5.29-30.0

…fixed #1083058 (Laurynas Biveinis). Upstream changes made to improve InnoDB DROP TABLE performance were not adjusted for XtraDB. This could cause … which wasn’t original intention. Bug fixed #1105709 (Laurynas Biveinis). INFORMATION_SCHEMA plugin name innodb_changed_pages serves also as a command…

Post: Announcing Percona Server 5.5.27-28.0

… administrative tasks but limited access to user schema. This feature is especially useful to those …type information for the undo segment. This information is ‘live’ and calculated for each query of the table. Bugs…and it’s setting up the innodb_lazy_drop_table to 1. Release notes for Percona Server …