21.29.8 The INFORMATION_SCHEMA INNODB_SYS_INDEXES Table

The INNODB_SYS_INDEXES table provides metadata about InnoDB indexes, equivalent to the information in the internal SYS_INDEXES table in the InnoDB data dictionary.

Table 21.9 INNODB_SYS_INDEXES Columns

Column nameDescription
INDEX_IDAn identifier for each index that is unique across all the databases in an instance.
NAMEThe name of the index. Most indexes created implicitly by InnoDB have consistent names but the index names are not necessarily unique. For example, PRIMARY for a primary key index, GEN_CLUST_INDEX for the index representing a primary key when one is not specified, and ID_IND, FOR_IND, and REF_IND for foreign key constraints.
TABLE_IDAn identifier representing the table associated with the index; the same value from INNODB_SYS_TABLES.TABLE_ID.
TYPEA numeric identifier signifying the kind of index. 0 = Secondary Index, 1 = Clustered Index, 2 = Unique Index, 3 = Primary Index, 32 = Full-text Index.
N_FIELDSThe number of columns in the index key. For the GEN_CLUST_INDEX indexes, this value is 0 because the index is created using an artificial value rather than a real table column.
PAGE_NOThe root page number of the index B-tree. For full-text indexes, the PAGE_NO field is unused and set to -1 (FIL_NULL) because the full-text index is laid out in several B-trees (auxiliary tables).
SPACEAn identifier for the tablespace where the index resides. 0 means the InnoDB system tablespace. Any other number represents a table created in file-per-table mode with a separate .ibd file. This identifier stays the same after a TRUNCATE TABLE statement. Because all indexes for a table reside in the same tablespace as the table, this value is not necessarily unique.

Example:

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_INDEXES WHERE TABLE_ID = 74 \G
*************************** 1. row ***************************
INDEX_ID: 116
    NAME: GEN_CLUST_INDEX
TABLE_ID: 74
    TYPE: 1
N_FIELDS: 0
 PAGE_NO: 3
   SPACE: 60
*************************** 2. row ***************************
INDEX_ID: 117
    NAME: i1
TABLE_ID: 74
    TYPE: 0
N_FIELDS: 1
 PAGE_NO: 4
   SPACE: 60
2 rows in set (0.00 sec)

Notes: