DROP INDEX
Removes
an index from a table.
SYNTAX
| index_name |
Name
of the index you want to remove. |
| table_name |
Name
of the table you want to remove the index from. |
DESCRIPTION
The DROP
INDEX command removes an existing index on a table from the database.
To execute the DROP INDEX command to drop an index from a table, you must
be the table owner, have DBA or SYSADM security privileges, or have the
INDEX privilege for that table.
An index
is a mechanism that provides fast access to specific rows in a table based
on the values of one or more columns from the table (known as the key).
Indexes contain the same data as the key columns from the table they are
based on, but the data is structured and sorted to make retrieval much
faster than the table. Once you create an index on a table, its operation
is transparent to users of the database; the DBMS will use the index to
improve query performance whenever possible.
You can
drop an index from any table in the database except the system tables.
DBMaker internally manages all indexes on the system tables, and will
not allow you to drop them. If an index has foreign keys that refer to
it, you must drop those foreign keys before you can drop the index. You
may want to drop an index if it becomes fragmented, which reduces its
efficiency. Rebuilding the index will create a denser, unfragmented index.
EXAMPLE
The following
example drops the index named NameIndex from the Employees table. If there
are any foreign keys which refer to NameIndex, you must drop the foreign
keys before you can drop NameIndex.
DROP INDEX NameIndex FROM Employees
|
RELATED COMMANDS
<
DROP GROUP | Contents
| DROP LINK >
|
