Determining the Row Format of a Table •The  REDUNDANT  and  COMPACT  row formats support a maximum index key prefix length of 767 bytes whereas  DYNAMIC  and  COMPRESSED  row formats support an index key prefix length of 3072 bytes. In a replication environment, if the  innodb_default_row_format  variable is set to  DYNAMIC  on the source, and set to  COMPACT  on the replica, the following DDL statement, which does not explicitly define a row format, succeeds on the source but fails on the replica: 3171 •Controlling the amount of background I/O used to improve query performance. This section discusses the main considerations for I/O and disk space with the default kind of MySQL tables (also known as  InnoDB  tables): As a DBA, you must manage disk I/O to keep the I/O subsystem from becoming saturated, and manage disk space to avoid filling up storage devices. The ACID design model requires a certain amount of I/ O that might seem redundant, but helps to ensure data reliability. Within these constraints,  InnoDB tries to optimize the database work and the organization of disk files to minimize the amount of disk I/O. Sometimes, I/O is postponed until the database is not busy, or until everything needs to be brought to a consistent state, such as during a database restart after a fast shutdown. 15.11 InnoDB Disk I/O and File Space Management mysql>  SELECT NAME, ROW_FORMAT FROM INFORMATION_SCHEMA.INNODB_TABLES WHERE NAME=’test1/t1’; +----------+------------+ | NAME | ROW_FORMAT | +----------+------------+ | test1/t1 | Dynamic | +----------+------------+ mysql>  SHOW TABLE STATUS IN test1\G *************************** 1. row *************************** Name: t1 Engine: InnoDB Version: 10 Row_format: Dynamic Rows: 0  Avg_row_length: 0 Data_length: 16384 Max_data_length: 0 Index_length: 16384 Data_free: 0  Auto_increment: 1 Create_time: 2016-09-14 16:29:38 Update_time: NULL Check_time: NULL Collation: utf8mb4_0900_ai_ci Checksum: NULL  Create_options: Comment: Alternatively, query the  INFORMATION_SCHEMA.INNODB_TABLES  table: To determine the row format of a table, use  SHOW TABLE STATUS CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 VARCHAR(5000), KEY i1(c2(3070))); For related information, see Section 15.22, “InnoDB Limits” . •Importing a table that does not explicitly define a row format results in a schema mismatch error if the innodb_default_row_format  setting on the source server differs from the setting on the destination server. For more information, see Section 15.6.1.3, “Importing InnoDB Tables” . Determining the Row Format of a Table