Append</literal> node can have both partial and non-partial child plans.
Non-partial children will be scanned by only a single process, since
scanning them more than once would produce duplicate results. Plans that
- involve appending multiple results sets can therefore achieve
+ involve appending multiple result sets can therefore achieve
coarse-grained parallelism even when efficient partial plans are not
available. For example, consider a query against a partitioned table
that can only be implemented efficiently by using an index that does