Design and Troubleshoot Calculations and Workbooks40% of the exam
Moving calculations upstream into Prep or databases
Decide which calculations belong in the database, a Tableau Prep flow or a materialized extract, and which must stay in the workbook: multi-grain LOD workarounds, cross-source and row-level logic, pre-aggregation for heavy table calculations, Compute Calculations Now and its exclusions, aggregate ratios, TODAY-based flags and static Prep ranks.
Recommend calculations that should be moved upstream of Tableau.
~7 min read · 6 practice questions ·
What the exam expects
- Recommend moving granularity workarounds, cross-source calculations and shared row-level logic into the database or a Tableau Prep flow.
- Recommend pre-aggregating in the source when a table calculation receives a very large result set.
- Use Compute Calculations Now where it helps, and name the calculations it cannot materialize.
- Keep in the workbook what must respond to the view: aggregate ratios, TODAY-based logic and ranks that should follow viewer filters.
Key terms:
- Upstream: any layer before the workbook (the database, a Prep flow or the extract) where work is done before a user opens a view.
- Materialized calculation: a calculation whose values are computed in advance and stored in the extract.
- Row-level expression: a calculation evaluated in each row of the underlying table.
- Aggregate calculation: an expression over aggregated fields, computed at the view's level of detail.
- Analytic function (Prep): a RANK or ROW_NUMBER calculation over a partition of rows in a flow.
Key facts
Upstream benefit
- Detail
- Processing done before the user requests the dashboard
Multiple data sources
- Detail
- Tableau can't optimize; computes locally
Prep FIXED syntax
- Detail
{FIXED [Field1],[Field2] : Aggregation([Field])}
Prep rank default
- Detail
- Descending; PARTITION optional, ORDERBY required
When to materialize
- Detail
- Slow extract queries from complex calculations
Materializing published extracts
- Detail
- Download, compute and republish, or tabcmd refreshextracts --addcalculations
Extract size
- Detail
- Materializing calculations can increase it
Aggregate calculation
- Detail
SUM(Sales) / SUM(Profit)is computed at view level
Scheduled flows
- Detail
- Prep Conductor, with Data Management
Sources for this section (5)
- Workbook Optimizerhelp.tableau.com (opens in a new tab)
- Prep LOD, Rank, and Tilehelp.tableau.com (opens in a new tab)
- Materialize Calculationshelp.tableau.com (opens in a new tab)
- How LOD Expressions Workhelp.tableau.com (opens in a new tab)
- Get Started with Tableau Prep Builderhelp.tableau.com (opens in a new tab)
- Why can ROW_NUMBER in a Prep flow give different results on each run?
- When are calculations on column groups materializable?
- Which output targets can a Prep flow write to?
- Why might an index help a field you use often as a context filter?
The questions are free to read. Answers with their sources and self-grading are included with the pack.
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