DAX (Half the Interview)
- CALCULATE explained? — modifies filter context; give YTD example.
- Measures vs calculated columns? — dynamic aggregation vs row-stored; prefer measures.
- Filter context vs row context? — with RELATED/iterators example.
- Time intelligence? — SAMEPERIODLASTYEAR, DATESYTD need date tables.
- Fix a slow measure? — variables, remove iterators, check cardinality.
Modelling + ETL
- Star vs snowflake? — star for speed/simplicity in Power BI.
- Bi-directional filters? — avoid; use single + bridge tables.
- Power Query steps? — connect → clean types → merge/append → load; fold queries.
- Incremental refresh? — policy on large datasets; Premium/pro implications.
Service, RLS, Deployment
- RLS how-to? — roles + DAX filters + test-as-role.
- Gateway? — on-prem refresh bridge.
- Publish flow? — Desktop → Service workspace → app; scheduled refresh.
Demo Round Wins Offers
Carry one sales dashboard: 3 DAX measures, drill-through, mobile view. Narrate insights, not clicks. Build it in Power BI training; practice DAX free with our guides.
10 More Rapid-Fire Questions (With Answers)
- Bookmarks vs buttons? — Bookmarks save view states; buttons trigger them (+ navigation/actions).
- Drillthrough setup? — Right-click pass filters to detail page via drillthrough filters.
- Composite models? — Mix Import + DirectQuery; aggregations tame big data.
- Aggregations? — Pre-summarised tables auto-hit for speed on huge models.
- Q&A visual? — Natural-language queries over the model; needs good synonyms/phrasing.
- Paginated reports use? — Pixel-perfect printable invoices/statements — different builder.
- Deployment pipelines? — Dev → Test → Prod workspace flow with rules.
- Workspace roles? — Admin/Member/Contributor/Viewer — least privilege.
- Why DAX variables? — VAR stores steps once: faster + readable + single evaluation.
- Dataflows vs datasets? — Dataflows = shared ETL entities; datasets = models/consumption layer.
7-Day Revision Plan
- Day 1–2: definitions aloud (record yourself, 2-min each).
- Day 3–4: 1 project end-to-end narration.
- Day 5: full mock with a friend/mentor.
- Day 6: fix weak answers only.
- Day 7: rest + revise flashcards. Sleep beats cramming.
Annotated Mock Round (BI Developer, 15 min)
- "Show your best dashboard." → Open it live: "3 DAX measures, drill-through to invoice grain, mobile layout." Click, don't describe. Demo > slides.
- "YTD is slow — fix live?" → "VAR the base, check iterators over fact, verify date table continuity." DAX depth proven.
- "Sales wants region-wise targets editable?" → "What-if parameters + disconnected table; note write-back needs Power Apps." Scope honesty.
- "RLS for 4 regions?" → "Roles + USERPRINCIPALNAME() mapping table; test-as-role demo." Security maturity.
Frequently Asked Questions
- Is DAX asked in every Power BI interview?
Yes — 40–50% weightage. CALCULATE + filter context decide rounds. - Power BI vs Tableau interviews?
DAX depth (PBI) vs LOD calcs (Tableau); learn one deeply. - Fresher BI salary?
₹3.5–7 LPA; dashboard demo adds ₹1–2 LPA leverage. - How to prepare in 30 days?
DAX daily + 1 dashboard + 3 mocks.
Read also: Learn Power BI · PBI Roadmap · PBI Projects