When deferred updates are required

Deferred updates are always required for:

Deferred updates are also required when:

Deferred updates incur more overhead than direct updates because they require Adaptive Server to reread the transaction log to make the final changes to the data and indexes. This involves additional traversal of the index trees.

For example, if there is a clustered index on title, this query performs a deferred update:

update titles set title = "Portable C Software" where title = "Designing Portable Software"