Parallel update and delete operations
Informix® performs some types of update and delete operations in parallel.
The database server takes the following two steps to process UPDATE
and DELETE statements:
- Fetches the qualifying rows.
- Applies the action of updating or deleting.
The database server performs the first step of an UPDATE or DELETE statement in parallel, with the following exceptions:
- The targeted table in a DELETE statement has a referential constraint that can cascade to a child table.
- The UPDATE or DELETE 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.