DROP INDEX

Function

Drops an index.

Precautions

Only the index owner, owner of the schema where the index resides, a user who has the INDEX permission on the table where the index resides, or a user who has the DROP ANY INDEX permission can run the DROP INDEX command. The system administrator has this permission by default.

For a global temporary table, if a session has initialized a global temporary table object (including creating a global temporary table and inserting data into the global temporary table for the first time), other sessions cannot delete indexes from the table.

Syntax

DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] 
    index_name [, ...] [ CASCADE | RESTRICT ];

Parameter Description

CONCURRENTLY
Deletes an index without locking it. When an index is deleted, other statements cannot access the table on which the index depends. With this option, the statement does not lock the table during index deletion.

This parameter can specify only one index name and does not support CASCADE.

The DROP INDEX statement can be run within a transaction, but DROP INDEX CONCURRENTLY cannot.
IF EXISTS
Reports a notice instead of an error if the specified index does not exist.
index_name
Specifies the index name to be deleted.

Value range: an existing index
CASCADE | RESTRICT
- CASCADE: automatically deletes the objects that depend on the index.
- RESTRICT: refuses to delete the index if any objects depend on it. This is the default action.