Module Review: Indexing Strategies

Congratulations on completing the Indexing Strategies module! You’ve moved beyond “just add an index” to understanding the internal structures and advanced optimizations that make Postgres unique.

1. Key Takeaways

  • B-Tree is King: Use it for 95% of queries (Equality, Range, Sorting). It’s the only index that enforces uniqueness.
  • GIN for Composites: Use GIN for JSONB containment (@>), Arrays (&&), and Full Text Search (@@). It maps keys to lists of TIDs.
  • GiST for Spatial/Custom: Use GiST for Geometric data (PostGIS), Ranges, and Nearest Neighbor (<->) searches.
  • Partial Indexes Save Space: Use a WHERE clause in your index definition to index only the rows that matter (e.g., WHERE status = 'active').
  • Covering Indexes for Speed: Use INCLUDE to add payload columns to leaf nodes, enabling Index-Only Scans.
  • VACUUM Matters: Index-Only Scans rely on the Visibility Map, which is updated by VACUUM.

2. Cheat Sheet: Which Index?

Data Type Query Pattern Recommended Index Example
Integer / Text Equality (=) B-Tree CREATE INDEX ON table (col);
Integer / Text Range (<, >) B-Tree CREATE INDEX ON table (col);
Text Prefix (LIKE 'abc%') B-Tree CREATE INDEX ON table (col text_pattern_ops);
JSONB Containment (@>) GIN CREATE INDEX ON table USING GIN (col);
JSONB Extract Key (->>) B-Tree (Expression) CREATE INDEX ON table ((col->>'key'));
Array Overlap (&&) GIN CREATE INDEX ON table USING GIN (col);
Geometry Intersection (&&) GiST CREATE INDEX ON table USING GIST (col);
Geometry Nearest (<->) GiST CREATE INDEX ON table USING GIST (col);
Full Text Match (@@) GIN CREATE INDEX ON table USING GIN (to_tsvector(...));

3. Flashcards

Test your understanding of the core concepts.

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4. Next Steps

Now that you’ve mastered indexing, it’s time to look at how to write queries that actually use them effectively.