A warehouse big enough that bad SQL actually hurts

Every question bank you've used so far seeds a handful of rows — a full table scan finishes instantly whether it's the right plan or not. This one is ~300,000 rides, no indexes to start. Read the plan, find the seq scan, fix it, and watch the timing move.

Beta — this track is under construction and will eventually move to Pro. It's included in Basic for free until then — once Data Lab is complete, Basic access ends.

Chapter 1

Add the index

Create a composite index on the same 300k-row table and watch the plan — and the timing — change.

2 steps Chapter 2

Why your query is slow

Read an EXPLAIN ANALYZE plan on a 300k-row table and find the seq scan that's costing you.

2 steps