DROP INDEX

Remove an existing index from a table. This command deletes the index structure, potentially impacting query performance but freeing storage.

Syntax

DROP INDEX [IF EXISTS] index_name ON tbl_name 
    [WAIT n |NOWAIT]

Description

DROP INDEX drops the index named index_name from the table tbl_name. This statement is mapped to an ALTER TABLE statement to drop the index.

If another connection is using the table, a metadata lock is active, and this statement will wait until the lock is released. This is also true for non-transactional tables.

See ALTER TABLE.

Another shortcut, CREATE INDEX, allows the creation of an index.

To remove the primary key, PRIMARY must be specified as index_name. Note that the quotes are necessary, because PRIMARY is a keyword.

Privileges

Executing the DROP INDEX statement requires the INDEX privilege for the table or the database.

Online DDL

Online DDL is used by default with InnoDB, when the drop index operation supports it.

See InnoDB Online DDL Overview for more information on online DDL with InnoDB.

DROP INDEX IF EXISTS ...

If the IF EXISTS clause is used, then MariaDB will return a warning instead of an error if the index does not exist.

WAIT/NOWAIT

Sets the lock wait timeout. See WAIT and NOWAIT.

Progress Reporting

MariaDB provides progress reporting for DROP INDEX statement for clients that support the new progress reporting protocol. For example, if you were using the mariadb client, then the progress report might look like this::

See Also

• Getting Started with Indexes

• CREATE INDEX

• ALTER TABLE

_{This page is licensed: GPLv2, originally from fill_help_tables.sql}