Indexing & Query Performance
Making queries fast without making writes slow.
Backend Engineer track
Junior
Write correct code, ship small changes safely, ask good questions.
- Database IndexA lookup structure that speeds up queries at the cost of slower writes.
- N+1 Query ProblemOne query for a list, then one more query for every item in it.
Mid-level
Own a feature end to end without hand-holding.
Core: start here
- Composite IndexAn index on several columns, where column order matters.
- Query OptimizationRewriting queries and adding indexes to make them fast.
4 more mid-level concepts
- B-TreeA wide, shallow tree optimized for disks; how database indexes work.
- Eager vs Lazy LoadingLoading related data upfront vs on first access.
- Slow Query LogA record of queries that take too long.
- Unique IndexAn index that also enforces uniqueness.
Senior
Own a system, its failure modes, and its trade-offs.
- Covering IndexAn index containing every column a query needs.
- Hash IndexAn index for equality lookups only.
- Index SelectivityHow well an index narrows down rows.
- Partial IndexAn index over only the rows matching a condition.
- Specialized Indexes (GIN, GiST, BRIN)Index types for JSON, full-text search, geometry and huge tables.
- Table StatisticsData distributions the planner uses to choose query plans.
- VACUUM and BloatCleaning up dead rows in PostgreSQL.
Staff
Shape how many teams build, across systems.
Nothing here yet.
Principal
Set technical direction for the organization.
Nothing here yet.
Data Analyst track
Junior
Write correct SQL, build trusted dashboards, ask good questions.
Nothing here yet.
Mid-level
Own an analysis end to end, from vague question to recommendation.
- Database IndexA lookup structure that speeds up queries at the cost of slower writes.
Senior
Own experimentation and metrics design; call out bad numbers.
Nothing here yet.
Staff
Shape how the organization measures and decides.
Nothing here yet.
Principal
Set measurement strategy across the company.
Nothing here yet.
Data Engineer track
Junior
Build and fix pipelines from clear specs; write correct SQL.
- Database IndexA lookup structure that speeds up queries at the cost of slower writes.
- N+1 Query ProblemOne query for a list, then one more query for every item in it.
Mid-level
Own pipelines and models end to end, including their quality.
- B-TreeA wide, shallow tree optimized for disks; how database indexes work.
- Composite IndexAn index on several columns, where column order matters.
- Eager vs Lazy LoadingLoading related data upfront vs on first access.
- Query OptimizationRewriting queries and adding indexes to make them fast.
- Slow Query LogA record of queries that take too long.
- Unique IndexAn index that also enforces uniqueness.
Senior
Design the platform's storage, processing and modeling choices.
- Covering IndexAn index containing every column a query needs.
- Hash IndexAn index for equality lookups only.
- Index SelectivityHow well an index narrows down rows.
- Partial IndexAn index over only the rows matching a condition.
- Specialized Indexes (GIN, GiST, BRIN)Index types for JSON, full-text search, geometry and huge tables.
- Table StatisticsData distributions the planner uses to choose query plans.
- VACUUM and BloatCleaning up dead rows in PostgreSQL.
Staff
Shape how the whole organization produces and uses data.
Nothing here yet.
Principal
Set data strategy and architecture across the company.
Nothing here yet.
Frontend Engineer track
Junior
Build UI that works, ship small changes safely, ask good questions.
- Database IndexA lookup structure that speeds up queries at the cost of slower writes.
- N+1 Query ProblemOne query for a list, then one more query for every item in it.
Mid-level
Own a feature end to end without hand-holding.
Nothing here yet.
Senior
Own an app's architecture, performance, and failure modes.
- B-TreeA wide, shallow tree optimized for disks; how database indexes work.
Staff
Shape how many teams build, across apps.
Nothing here yet.
Principal
Set technical direction for the organization.
Nothing here yet.