Reshaping & aggregating — quiz

A new month column appears in the source each month. Use:

1. A manual pivot, updated monthly
2. A wildcard pivot
3. A union
4. A join

Answer: A wildcard pivot — It matches columns that do not exist yet.

For data Tableau will analyse, pivot:

1. Rows to columns
2. Columns to rows
3. Neither
4. Both

Answer: Columns to rows — Long form gives one dimension and one measure rather than many measures.

To prevent a join multiplying rows, add an aggregate step:

1. After the join
2. On the many side before the join
3. At the output
4. On the one side

Answer: On the many side before the join — Grouping by the join key gives one row per key.

The difference between an aggregate step and a FIXED LOD:

1. None
2. The aggregate step changes the grain; FIXED keeps every row
3. FIXED is faster
4. Aggregate works on text only

Answer: The aggregate step changes the grain; FIXED keeps every row — The same distinction as GROUP BY versus a window function.