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ALTER INDEX

Activates or deactivates an index, and rebuilds an index

Available in

DSQL, ESQL

Syntax
ALTER INDEX indexname {ACTIVE | INACTIVE}
Table 1. ALTER INDEX Statement Parameter
Parameter Description

indexname

Index name

The ALTER INDEX statement activates or deactivates an index.There is no facility on this statement for altering any attributes of the index.

INACTIVE

With the INACTIVE option, the index is switched from the active to inactive state.The effect is similar to the DROP INDEX statement except that the index definition remains in the database.Altering a constraint index to the inactive state is not permitted.

An active index can be deactivated if there are no queries prepared using that index;otherwise, an “object in use” error is returned.

Activating an inactive index is also safe.However, if there are active transactions modifying the table, the transaction containing the ALTER INDEX statement will fail if it has the NOWAIT attribute.If the transaction is in WAIT mode, it will wait for completion of concurrent transactions.

On the other side of the coin, if our ALTER INDEX succeeds and starts to rebuild the index at COMMIT, other transactions modifying that table will fail or wait, according to their WAIT/NO WAIT attributes.The situation is the same for CREATE INDEX.

Note
How is it Useful?

It might be useful to switch an index to the inactive state whilst inserting, updating or deleting a large batch of records in the table that owns the index.
ACTIVE

Rebuilds the index (even if already active), and marks it as active.

Note
How is it Useful?

Even if the index is active when ALTER INDEX …​ ACTIVE is executed, the index will be rebuilt.Rebuilding indexes can be a useful piece of housekeeping to do, occasionally, on the indexes of a large table in a database that has frequent inserts, updates or deletes but is infrequently restored.

Who Can Alter an Index?

The ALTER INDEX statement can be executed by:

  • Administrators

  • The owner of the table

  • Users with the ALTER ANY TABLE privilege