41. What is the difference between Data Source Filters, Extract Filters, and Context Filters?
| Filter | Applied At | Purpose |
|---|---|---|
| Extract Filter | Before extract creation | Reduces extract size |
| Data Source Filter | At data source level | Restricts data for all worksheets |
| Context Filter | Before dimension filters | Improves performance and controls filter order |
Interview Tip:
- Extract Filter → Reduces data stored in the extract.
- Data Source Filter → Applies to all worksheets using that data source.
- Context Filter → Creates a temporary table and is useful for dependent filters.
42. Explain Tableau's Query Pipeline (Order of Operations).
This determines the sequence in which Tableau executes filters and calculations.
Extract Filter ↓ Data Source Filter ↓ Context Filter ↓ FIXED LOD ↓ Dimension Filter ↓ INCLUDE / EXCLUDE LOD ↓ Measure Filter ↓ Table Calculation ↓ Forecast / Trend Line
Interview Tip: This is one of the most frequently asked conceptual questions because it explains why filters sometimes don't affect calculations.
43. What is the difference between FIXED, INCLUDE, and EXCLUDE LOD? Give a business example.
FIXED
Calculates at a fixed level, regardless of the view.
{ FIXED [Region] : SUM([Sales]) }
Use Case: Total sales by Region even if City is in the view.
INCLUDE
Adds dimensions to the current view.
{ INCLUDE [Customer Name] : SUM([Sales]) }
Use Case: Calculate average customer sales while viewing data by Region.
EXCLUDE
Removes dimensions from the current view.
{ EXCLUDE [City] : SUM([Sales]) }
Use Case: Show State-level sales while City is displayed in the visualization.
44. What is Performance Recorder, and how do you use it?
Performance Recorder helps identify slow-performing dashboards and queries.
Steps:
- Go to Help → Settings and Performance → Start Performance Recording.
- Open the dashboard.
- Stop recording.
-
Tableau generates a report showing:
- Query execution time
- Rendering time
- Layout computation
- Slow worksheets
- Slow calculations
Interview Tip: Mention that you use Performance Recorder to identify bottlenecks before optimizing filters, joins, or calculations.
45. How do you optimize a Tableau workbook with millions of records?
Best Practices:
- Use Extracts instead of Live Connections where possible.
- Use Relationships instead of unnecessary joins.
- Push heavy calculations to SQL or the database.
- Create Context Filters for highly selective filters.
- Reduce the number of marks displayed.
- Remove unused fields and worksheets.
- Avoid nested LODs and complex table calculations.
- Aggregate data before loading into Tableau.
- Index key columns in the database.
- Use the Performance Recorder to identify bottlenecks.
Interview Tip: For senior roles, explain optimization at three levels:
- Database (indexes, optimized SQL, aggregation)
- Data Model (relationships, extracts, fewer joins)
- Visualization (fewer marks, efficient filters, simpler calculations)
These answers demonstrate practical experience rather than just theoretical knowledge.
