Worktable created for DISTINCT

When a query that includes the DISTINCT keyword is issued, all duplicate rows are excluded from the results and only unique rows are returned. To accomplish this, SQL Server first creates a worktable to store the results of the query, including duplicates, just as if the DISTINCT keyword were not included. It then sorts the rows in the worktable and discards the duplicate rows. Finally, the rows from the worktable are returned, ensuring that no duplicate rows will appear in the output.

Query:

SELECT DISTINCT city
FROM authors

SHOWPLAN:

STEP 1
The type of query is INSERT
The update mode is direct
Worktable created for DISTINCT
FROM TABLE
authors
Nested iteration
Table Scan
TO TABLE
Worktable 1

STEP 2
The type of query is SELECT
This step involves sorting
FROM TABLE
Worktable 1
Using GETSORTED Table Scan