IBM® Informix® performs some types of update operations in parallel.
The database server takes the following two steps to process UPDATE statements:
1. Fetches the qualifying rows.
2. Applies the action of updating.
The database server performs the first step of an UPDATE statement in parallel, with the following exceptions:
- The UPDATE statement contains an OR clause and the optimizer chooses an OR index to process the OR filter.
- The UPDATE statement contains a subquery that the optimizer converts into a join.