Deferred (Index Keyword)
Usage
To specify that the index is deferred, use the following syntax:
Index name [ Deferred ];
Where name is the name of the index. It is useful to follow a naming convention so that indexes can be easily distinguished from properties. For example, you could include IDX at the end of all index names.
Details
A deferred index is not updated automatically when a new record is inserted or updated, but is instead flagged as having work left to do at a later time by a backfilling operation. This is a design decision that requires you to weigh the performance benefits that deferred insertion or updating bring to the efficiency of your application against querying potentially stale data in the index.
Default
The default for the Deferred keyword is false.
Requirements
The table must have a bitmap-compatible ID.
For an index to be Deferred, it cannot have IdKey=1, PrimaryKey=1, or Unique=1, as those keywords imply integrity rules that cannot be deferred.
If an index is based on a property that is marked as Deferred, the index must also be marked as deferred.
