The query processor uses a virtually hashed index only if
you include search arguments that include an equality qualifier
(for example, where id=2)
on all key columns. If the query processor uses the virtually hashed
index, it includes a line similar to this in the showplan output:
Using Virtually Hashed Index.
The query processor includes lines similar to this in the index selection output if it selects a virtually hashed index:
Unique virtually hashed index found, returns 1 row, 1 pages
