Parallel update operations

Product documentation


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.

Related information

12:10 - Database server operations that use PDQ
11:70 - Database server operations that use PDQ

Product Alias/Synonym


Document information

More support for:

Informix Servers

Software version:

11.5, 11.7, 11.70, 12.1

Operating system(s):

AIX, HP-UX, Linux, OS X, Solaris, Windows

Reference #:


Modified date:


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