This step involves sorting.
This showplan message indicates that the query must sort the intermediate results before returning them to the user. Queries that use distinct or that have an order by clause not supported by an index require an intermediate sort. The results are put into a worktable, and the worktable is then sorted.
For examples of this message, see “Worktable message for distinct” on page 810 and “Worktable message for order by” on page 811.