Dashboard Design
lick customer → opens their CRM profile | | Go to Sheet | Navigates to another worksheet | Click summary → opens detailed drill-down sheet |
8. Live vs Extract Connection
| Feature | Live | Extract |
|---|---|---|
| What it is | Real-time connection to database | A local copy of data (.hyper file) |
| Speed | Slower (queries run each time) | Faster (pre-computed local copy) |
| Data freshness | Always latest | Depends on scheduled refresh |
| Best for | Real-time monitoring dashboards | Historical analysis, slow databases |
| File format | N/A | .hyper (Tableau 10.5+), .tde (legacy) |
🧠 Interview mein bolo: "I'd use Extract for most cases — faster, reduces load on the source database. I'd schedule daily/hourly refreshes based on the client's needs. Live connection sirf jab real-time data critical ho."
9. Parameters
A parameter is a dynamic value that can be used in calculated fields, filters, and reference lines. The user can control it from the view.
Common Uses:
- Dynamic Top N: Let users choose "Show Top 5/10/20 products"
- Reference Line: Let users set a target line on a chart
- Metric Switcher: Let users toggle between Revenue, Profit, and Quantity
Example: Dynamic Top N
Step 1: Create Parameter → Name: "Top N", Type: Integer, Default: 10
Step 2: Create Calculated Field →
RANK(SUM([Sales])) <= [Top N Parameter]
Step 3: Drag to filter → Keep TRUE values
Step 4: Show parameter control on dashboard
10. Interview Questions (12 Questions)
Q1: "Difference between Discrete and Continuous?"
Answer: "Discrete creates separate headers — like individual bars for each month. Continuous creates a flowing axis — like a smooth timeline. In Tableau, blue pills are discrete, green pills are continuous. The same field — like Date — can be either. As Discrete Month, you get 12 bars; as Continuous Month, you get a smooth line."
Q2: "What is a Context Filter and when would you use it?"
Answer: "A Context Filter creates a temporary subset of data before other filters are applied. I'd use it when I need Top N analysis within a filtered group — for example, Top 5 products in a specific region. Without Context Filter, Tableau finds Top 5 across all regions first, then applies the region filter, which gives incorrect results."
Q3: "Explain LOD expressions with an example."
Answer: "LOD expressions compute aggregations at a different granularity than the view. For example, FIXED [Region] : SUM([Sales]) calculates total regional sales regardless of what the view shows. If my view is at the product level, each product row will still show its region's total — useful for calculating each product's percentage contribution to the region."
Q4: "How do you handle performance issues in Tableau?"
Answer: "Five strategies: (1) Use Extracts instead of Live connections — pre-computed data is faster. (2) Add Data Source filters to avoid loading unnecessary data. (3) Pre-aggregate at the source — aggregate in SQL before bringing data to Tableau. (4) Reduce marks — too many data points slow rendering. (5) Use Context Filters to limit the working dataset before other filters run."
Q5: "Difference between blending and joining?"
Answer: "JOINs combine data at the data source level into a single merged table. Blending combines data from two different sources at the visualization level — Tableau queries them separately and links results. I'd use JOINs when data is in the same