InnoDB INFORMATION_SCHEMA Schema Object Tables col1 INT, col2 CHAR(10), col3 VARCHAR(10)) ENGINE = InnoDB; mysql>  CREATE INDEX i1 ON t1(col1); mysql>  SELECT * FROM INFORMATION_SCHEMA.INNODB_TABLES WHERE NAME=’test/t1’ \G *************************** 1. row *************************** TABLE_ID: 71 NAME: test/t1 FLAG: 1 N_COLS: 6 SPACE: 57 ROW_FORMAT: Compact ZIP_PAGE_SIZE: 0  INSTANT_COLS: 0 mysql>  SELECT * FROM INFORMATION_SCHEMA.INNODB_COLUMNS where TABLE_ID = 71\G *************************** 1. row *************************** TABLE_ID: 71 NAME: col1 POS: 0 MTYPE: 6 PRTYPE: 1027 LEN: 4 HAS_DEFAULT: 0 DEFAULT_VALUE: NULL *************************** 2. row *************************** TABLE_ID: 71 NAME: col2 POS: 1 MTYPE: 2 PRTYPE: 524542 LEN: 10 HAS_DEFAULT: 0 DEFAULT_VALUE: NULL *************************** 3. row *************************** TABLE_ID: 71 NAME: col3 POS: 2 MTYPE: 1 PRTYPE: 524303 LEN: 10 HAS_DEFAULT: 0 DEFAULT_VALUE: NULL In addition to the  TABLE_ID  and column  NAME ,  INNODB_COLUMNS  provides the ordinal position ( POS ) of each column (starting from 0 and incrementing sequentially), the column  MTYPE  or “main type”  (6 = INT, 2 = CHAR, 1 = VARCHAR), the  PRTYPE  or “precise type”  (a binary value with bits that represent the MySQL data type, character set code, and nullability), and the column length ( LEN ). The 3309 3. Using the  TABLE_ID  information from  INNODB_TABLES , query the  INNODB_COLUMNS  table for information about the table’s columns. Table  t1  has a  TABLE_ID  of 71. The  FLAG  field provides bit level information about table format and storage characteristics. There are six columns, three of which are hidden columns created by InnoDB  ( DB_ROW_ID ,  DB_TRX_ID , and  DB_ROLL_PTR ). The ID of the table’s  SPACE  is 57 (a value of 0 would indicate that the table resides in the system tablespace). The  ROW_FORMAT  is Compact. ZIP_PAGE_SIZE  only applies to tables with a  Compressed  row format.  INSTANT_COLS  shows number of columns in the table prior to adding the first instant column using  ALTER TABLE ... ADD COLUMN  with  ALGORITHM=INSTANT . 2. After creating the table  t1 , query  INNODB_TABLES  to locate the metadata for  test/t1 :