TIDB_INDEXES

The TIDB_INDEXES table provides the INDEX information of all tables.

USE information_schema; DESC tidb_indexes;
+---------------+---------------+------+------+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------+---------------+------+------+---------+-------+ | TABLE_SCHEMA | varchar(64) | YES | | NULL | | | TABLE_NAME | varchar(64) | YES | | NULL | | | NON_UNIQUE | bigint(21) | YES | | NULL | | | KEY_NAME | varchar(64) | YES | | NULL | | | SEQ_IN_INDEX | bigint(21) | YES | | NULL | | | COLUMN_NAME | varchar(64) | YES | | NULL | | | SUB_PART | bigint(21) | YES | | NULL | | | INDEX_COMMENT | varchar(2048) | YES | | NULL | | | Expression | varchar(64) | YES | | NULL | | | INDEX_ID | bigint(21) | YES | | NULL | | +---------------+---------------+------+------+---------+-------+ 10 rows in set (0.00 sec)

INDEX_ID is the unique ID that TiDB allocates for each index. It can be used to do a join operation with INDEX_ID obtained from another table or API.

For example, you can obtain TABLE_ID and INDEX_ID that are involved in some slow query in the SLOW_QUERY table and then obtain the specific index information using the following SQL statements:

SELECT tidb_indexes.* FROM tidb_indexes, tables WHERE tidb_indexes.table_schema = tables.table_schema AND tidb_indexes.table_name = tidb_indexes.table_name AND tables.tidb_table_id = ? AND index_id = ?

Fields in the TIDB_INDEXES table are described as follows:

  • TABLE_SCHEMA: The name of the schema to which the index belongs.
  • TABLE_NAME: The name of the table to which the index belongs.
  • NON_UNIQUE: If the index is unique, the value is 0; otherwise, the value is 1.
  • KEY_NAME: The index name. If the index is the primary key, the name is PRIMARY.
  • SEQ_IN_INDEX: The sequential number of columns in the index, which starts from 1.
  • COLUMN_NAME: The name of the column where the index is located.
  • SUB_PART: The prefix length of the index. If the the column is partly indexed, the SUB_PART value is the count of the indexed characters; otherwise, the value is NULL.
  • INDEX_COMMENT: The comment of the index, which is made when the index is created.
  • INDEX_ID: The index ID.

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