Indexing deep-dive: SQL & NoSQL

PostgreSQL · MySQL · MongoDB · 6 scenarios

Prototype — data is mocked and actions are not connected yet.

← Goals

PostgreSQLMySQLMongoDB L1–L2

Composite order, selectivity and covering indexes — across relational and document systems side by side, so the instinct transfers between them.

3 / 6 scenarios passedScore avg 84%
Due Aug 1, 2026 · 8 weeks left

Scenarios to pass

PostgreSQL Query performance · L1 Wrong column order in a composite index 88% Passed
MySQL Query & indexing · L1 Wrong index column order 84% Passed
MongoDB Query & indexes · L1 Wrong index field order 80% Passed
MySQL Query & indexing · L2 Covering index missing — In progress
MongoDB Query & indexes · L2 Low-selectivity index — Not started
PostgreSQL Query performance · L2 Low-selectivity index trap — Not started

How this goal was set

  • SystemsPostgreSQL · MySQL · MongoDB
  • LevelMid
  • Focus areaIndexing
  • IntensityStandard · 6 scenarios

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Prototype — scenario scores are mocked.