SQL Server : Drop vs Disable Index

If you are dropping the index; the database will not have any information for dropped index and once the index is dropped, the metadata, statistics and index pages are removed.

But if you disable the existing index of table; database have the metadata of index but it will deallocate index page and the space is freed in database.

 

Here is a script to drop the SQL index from table

 

DROP INDEX OrderNumber_IX ON dbo.Order;

 

To drop all indexes of table

 

DROP INDEX ALL ON dbo.Order;

 

Here is a script to disable an index on table

 

ALTER INDEX OrderNumber_IX ON dbo.Order

Disable;

 

To disable all indexes of table

 

ALTER INDEX ALL ON dbo.Order

Disable;

 

Note : There is one additional data impact of  disabling the clustered index of table;  table will not be available for any DML operation except rebuild and drop command; so before disable clustered index; be very caution about its impact.

 

If you want to enable the disabled index on table; simply run the rebuild command

 

To enable a disabled index of table

 

ALTER INDEX OrderNumber_IX ON dbo.Order

rebuild;

 

To enable the all disabled index of table

 

ALTER INDEX ALL ON dbo.Order

rebuild;