24.4.17 The INFORMATION_SCHEMA INNODB_SYS_COLUMNS Table

The INNODB_SYS_COLUMNS table provides metadata about InnoDB table columns, equivalent to the information from the SYS_COLUMNS table in the InnoDB data dictionary.

For related usage information and examples, see Section 14.16.3, “InnoDB INFORMATION_SCHEMA System Tables”.

The INNODB_SYS_COLUMNS table has these columns:

• TABLE_ID

  An identifier representing the table associated with the column; the same value as INNODB_SYS_TABLES.TABLE_ID.

• NAME

  The name of the column. These names can be uppercase or lowercase depending on the lower_case_table_names setting. There are no special system-reserved names for columns.

• POS

  The ordinal position of the column within the table, starting from 0 and incrementing sequentially. When a column is dropped, the remaining columns are reordered so that the sequence has no gaps. The POS value for a virtual generated column encodes the column sequence number and ordinal position of the column. For more information, see the POS column description in Section 24.4.26, “The INFORMATION_SCHEMA INNODB_SYS_VIRTUAL Table”.

• MTYPE

  Stands for “main type”. A numeric identifier for the column type. 1 = VARCHAR, 2 = CHAR, 3 = FIXBINARY, 4 = BINARY, 5 = BLOB, 6 = INT, 7 = SYS_CHILD, 8 = SYS, 9 = FLOAT, 10 = DOUBLE, 11 = DECIMAL, 12 = VARMYSQL, 13 = MYSQL, 14 = GEOMETRY.

• PRTYPE

  The InnoDB “precise type”, a binary value with bits representing MySQL data type, character set code, and nullability.

• LEN

  The column length, for example 4 for INT and 8 for BIGINT. For character columns in multibyte character sets, this length value is the maximum length in bytes needed to represent a definition such as VARCHAR(N); that is, it might be 2*N, 3*N, and so on depending on the character encoding.

Example

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mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_COLUMNS where TABLE_ID = 71\G
*************************** 1. row ***************************
TABLE_ID: 71
    NAME: col1
     POS: 0
   MTYPE: 6
  PRTYPE: 1027
     LEN: 4
*************************** 2. row ***************************
TABLE_ID: 71
    NAME: col2
     POS: 1
   MTYPE: 2
  PRTYPE: 524542
     LEN: 10
*************************** 3. row ***************************
TABLE_ID: 71
    NAME: col3
     POS: 2
   MTYPE: 1
  PRTYPE: 524303
     LEN: 10

Notes

• You must have the PROCESS privilege to query this table.

• Use the INFORMATION_SCHEMA COLUMNS table or the SHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.