MySQL COUNT(*) Performance

MySQL COUNT(*) Performance is a SQL statement in the MySQL Specific category. MySQL InnoDB COUNT(*) is slow for large tables. MyISAM stores row count. Use estimates or counters. The syntax is SELECT COUNT(*) FROM t;. It returns row count info. 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. More about this category: MySQL-specific features — AUTO_INCREMENT, ENGINE, SHOW TABLES, LIMIT. Related MySQL Specific entries: AUTO_INCREMENT, ENGINE, LAST_INSERT_ID(), ON DUPLICATE KEY UPDATE, LOAD DATA INFILE, LOCK TABLES / UNLOCK TABLES, FIND_IN_SET(), CHARACTER SET / COLLATION.