PERFORMANCE_SCHEMA (MySQL)
PERFORMANCE_SCHEMA (MySQL) is a SQL statement in the MySQL Specific category. MySQL 5.6+: built-in performance monitoring views for query profiling, waits, and resource usage. The syntax is SELECT * FROM performance_schema.events_statements_summary_by_digest ORDER BY sum_timer_wait DESC;. It returns performance metrics. A typical example: -- Top queries by total execution time: SELECT DIGEST_TEXT, COUNT_STAR, SUM_TIMER_WAIT/1e12 AS total_sec, AVG_TIMER_WAIT/1e12 AS avg_sec FROM performance_schema.events_statements_summary_by_digest ORDER BY SUM_TIMER_WAIT DESC LIMIT 10; -- Table I/O statistics: SELECT OBJECT_SCHEMA, OBJECT_NAME, COUNT_FETCH, COUNT_INSERT, COUNT_UPDATE, COUNT_DELETE FROM performance_schema.table_io_waits_summary_by_table ORDER BY COUNT_FETCH + COUNT_INSERT + COUNT_UPDATE + COUNT_DELETE DESC LIMIT 10; A close relative is AUTO_INCREMENT, which mySQL auto-generates sequential integer values for this column. Commonly used with PRIMARY KEY. A close relative is ENGINE, which specifies the MySQL storage engine. InnoDB (default) supports transactions and foreign keys. MyISAM is faster for read-heavy. A close relative is LAST_INSERT_ID(), which returns the AUTO_INCREMENT value generated by the most recent INSERT in the current connection.