Role track

BI Analyst

Warehouse SQL at dashboard grain. Serving layers that are not your OLTP.

124 questions · SQL · Warehouse · Trino / CH · Modeling

Suggested sequence

1. 1. Whiteboard SQL

   Windows, ranking, and anti-joins with test cases.

   BI coding →

2. 2. The flowchart

   Facts, date grain, and a refresh that survives.

   BI roadmap →

3. 3. The warehouse dialect

   Slots, credits, or a MergeTree — pick the one you will defend.

   Warehouse bank →

4. 4. Do not query prod

   Replica, CDC, or a serving mart. Federated scans of OLTP fail the loop.

   Postgres questions →

Stacks in this loop

Sample questions

• hard · SQL · Stripe

  Deduplicate to the latest customer row. Why not filter the window in WHERE?

  Practice →

• medium · SQL · Capital One

  A join exploded revenue. How do you find the grain mismatch in five minutes?

  Practice →

• medium · SQL · Meta

  Running total of daily revenue. Why is SUM(SUM(amount)) OVER (...) valid?

  Practice →

• hard · SQL · Google

  NULL = NULL is unknown. How does that bite a MERGE or an anti-join?

  Practice →

• hard · SQL · LinkedIn

  When do you use a covering index / clustering key versus rewriting the query?

  Practice →

• medium · SQL · Snowflake

  QUALIFY vs a CTE for window filters — when do you use each?

  Practice →