Online index management

SQL Server 2019 introduces resumable online index creation in addition to rebuilding. The online option supports concurrent user access to the underlying table or index data during online index operations. Online index operations are recommended for business environments that require concurrent user activity during index operations for workloads that are online 24 hours a day and 7 days a week.

The ONLINE option is available in the following T-SQL statements:

• CREATE INDEX
• ALTER INDEX
• DROP INDEX
• ALTER TABLE (to add or drop UNIQUE or PRIMARY KEY constraints with the CLUSTERED index option)

When creating or rebuilding an index and the ONLINE option is set to ON, the underlying objects are available for querying and data modification. It is also possible to rebuild part of an index on a single partition.

Enabling online DML processing

To perform online index operations, the user requires ALTER permission on the table or view...