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MySQL Reference Manual :: 13.5.4.11 SHOW INDEX Syntax
Search the MySQL manual:
- 13.5.4 SHOW Syntax
- 13.5.4.1 SHOW CHARACTER SET Syntax
- 13.5.4.2 SHOW COLLATION Syntax
- 13.5.4.3 SHOW COLUMNS Syntax
- 13.5.4.4 SHOW CREATE DATABASE Syntax
- 13.5.4.5 SHOW CREATE TABLE Syntax
- 13.5.4.6 SHOW DATABASES Syntax
- 13.5.4.7 SHOW ENGINE Syntax
- 13.5.4.8 SHOW ENGINES Syntax
- 13.5.4.9 SHOW ERRORS Syntax
- 13.5.4.10 SHOW GRANTS Syntax
- 13.5.4.11 SHOW INDEX Syntax
- 13.5.4.12 SHOW INNODB STATUS Syntax
- 13.5.4.13 SHOW LOGS Syntax
- 13.5.4.14 SHOW PRIVILEGES Syntax
- 13.5.4.15 SHOW PROCESSLIST Syntax
- 13.5.4.16 SHOW STATUS Syntax
- 13.5.4.17 SHOW TABLE STATUS Syntax
- 13.5.4.18 SHOW TABLES Syntax
- 13.5.4.19 SHOW VARIABLES Syntax
- 13.5.4.20 SHOW WARNINGS Syntax
Additional languages
Additional formats
SHOW INDEX FROMtbl_name[FROMdb_name]
SHOW INDEX returns table index information in a
format that resembles the SQLStatistics call in
ODBC.
SHOW INDEX returns the following fields:
-
TableThe name of the table.
-
Non_unique0 if the index can't contain duplicates, 1 if it can.
-
Key_nameThe name of the index.
-
Seq_in_indexThe column sequence number in the index, starting with 1.
-
Column_nameThe column name.
-
CollationHow the column is sorted in the index. In MySQL, this can have values '
A' (Ascending) orNULL(Not sorted). -
CardinalityThe number of unique values in the index. This is updated by running
ANALYZE TABLEor myisamchk -a.Cardinalityis counted based on statistics stored as integers, so it's not necessarily accurate for small tables. The higher the cardinality, the greater the chance that MySQL uses the index when doing joins. -
Sub_partThe number of indexed characters if the column is only partly indexed.
NULLif the entire column is indexed. -
PackedIndicates how the key is packed.
NULLif it is not. -
NullContains
YESif the column may containNULL. If not, the column containsNOas of MySQL 5.0.3, and''before that. -
Index_typeThe index method used (
BTREE,FULLTEXT,HASH,RTREE). -
CommentVarious remarks. Before MySQL 4.0.2 when the
Index_typecolumn was added,Commentindicates whether an index isFULLTEXT.
The Packed and Comment
columns were added in MySQL 3.23.0. The Null and
Index_type columns were added in MySQL 4.0.2.
You can use db_name.tbl_name as an
alternative to the tbl_name
FROM db_name
mysql> SHOW INDEX FROM mytable FROM mydb; mysql> SHOW INDEX FROM mydb.mytable;
SHOW KEYS is a synonym for SHOW
INDEX. You can also list a table's indexes with the
mysqlshow -k db_name
tbl_name command.
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