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The DROP INDEX statement removes indexes from tables.
Note:
This statement performs a schema change. For more information about how online schema changes work in CockroachDB, see Online Schema Changes.
Synopsis
Required privileges
The user must have the CREATE privilege on each specified table.
Parameters
| Parameter | Description |
|---|---|
IF EXISTS |
Drop the named indexes if they exist; if they do not exist, do not return an error. |
table_name |
The name of the table with the index you want to drop. Find table names with SHOW TABLES. |
index_name |
The name of the index you want to drop. Find index names with SHOW INDEX.You cannot drop a table's primary index. |
CASCADE |
Drop all objects (such as constraints) that depend on the indexes. CASCADE does not list objects it drops, so should be used cautiously.New in v19.2: To drop an index created with CREATE UNIQUE INDEX, you do not need to use CASCADE. |
RESTRICT |
(Default) Do not drop the indexes if any objects (such as constraints) depend on them. |
Viewing schema changes
This schema change statement is registered as a job. You can view long-running jobs with SHOW JOBS.
Examples
Remove an index (no dependencies)
> SHOW INDEX FROM tl;
+------------+-------------+------------+--------------+-------------+-----------+---------+----------+
| table_name | index_name | non_unique | seq_in_index | column_name | direction | storing | implicit |
+------------+-------------+------------+--------------+-------------+-----------+---------+----------+
| t1 | primary | false | 1 | id | ASC | false | false |
| t1 | t1_name_idx | true | 1 | name | ASC | false | false |
| t1 | t1_name_idx | true | 2 | id | ASC | false | true |
+------------+-------------+------------+--------------+-------------+-----------+---------+----------+
(3 rows)
> DROP INDEX t1@t1_name_idx;
> SHOW INDEX FROM tbl;
+------------+------------+------------+--------------+-------------+-----------+---------+----------+
| table_name | index_name | non_unique | seq_in_index | column_name | direction | storing | implicit |
+------------+------------+------------+--------------+-------------+-----------+---------+----------+
| t1 | primary | false | 1 | id | ASC | false | false |
+------------+------------+------------+--------------+-------------+-----------+---------+----------+
(1 row)
Remove an index and dependent objects with CASCADE
Warning:
CASCADE drops all dependent objects without listing them, which can lead to inadvertent and difficult-to-recover losses. To avoid potential harm, we recommend dropping objects individually in most cases.> SHOW INDEX FROM orders;
+------------+---------------------------------------------+------------+--------------+-------------+-----------+---------+----------+
| table_name | index_name | non_unique | seq_in_index | column_name | direction | storing | implicit |
+------------+---------------------------------------------+------------+--------------+-------------+-----------+---------+----------+
| orders | primary | false | 1 | id | ASC | false | false |
| orders | orders_auto_index_fk_customer_ref_customers | true | 1 | customer | ASC | false | false |
| orders | orders_auto_index_fk_customer_ref_customers | true | 2 | id | ASC | false | true |
+------------+---------------------------------------------+------------+--------------+-------------+-----------+---------+----------+
(3 rows)
> DROP INDEX orders_auto_index_fk_customer_ref_customers;
pq: index "orders_auto_index_fk_customer_ref_customers" is in use as a foreign key constraint
> SHOW CONSTRAINTS FROM orders;
+------------+---------------------------+-----------------+--------------------------------------------------+-----------+
| table_name | constraint_name | constraint_type | details | validated |
+------------+---------------------------+-----------------+--------------------------------------------------+-----------+
| orders | fk_customer_ref_customers | FOREIGN KEY | FOREIGN KEY (customer) REFERENCES customers (id) | true |
| orders | primary | PRIMARY KEY | PRIMARY KEY (id ASC) | true |
+------------+---------------------------+-----------------+--------------------------------------------------+-----------+
(2 rows)
> DROP INDEX orders_auto_index_fk_customer_ref_customers CASCADE;
> SHOW CONSTRAINTS FROM orders;
+------------+-----------------+-----------------+----------------------+-----------+
| table_name | constraint_name | constraint_type | details | validated |
+------------+-----------------+-----------------+----------------------+-----------+
| orders | primary | PRIMARY KEY | PRIMARY KEY (id ASC) | true |
+------------+-----------------+-----------------+----------------------+-----------+
(1 row)
See Also
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