BigData / Tableau Interview Questions
What is the difference between a calculated field and a table calculation?
Both create derived values, but they operate at fundamentally different points in Tableau's query pipeline, which changes what each one can and can't do.
| Calculated Field | Table Calculation |
| Computed as part of the underlying query (row-level or aggregate). | Computed after the query returns, on the already-aggregated view. |
| Result doesn't depend on what else is in the view. | Result depends on the view's structure (partitioning/addressing). |
| Can be used across different views without recomputation concerns. | Tied to the specific view it's built for; moving it can change results. |
| Good for: ratios, IF/CASE logic, string/date manipulation. | Good for: rank, running total, percent of total, moving average. |
A simple diagnostic: if a calculation's correct result depends on knowing what other rows are currently visible in the view (like "what rank is this among the rows shown"), it needs to be a table calculation; if it only depends on that row's own values, a regular calculated field is the right tool.
Which type of calculation's result can change simply by rearranging the view it's placed in?
Which is the right tool for a simple Profit Ratio calculation that doesn't depend on other rows?
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