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Database Indexing Strategies

Database Indexing Strategies

Database Indexing Strategies

Database Indexing Strategies

Database Indexing Strategies

Database Indexing Strategies

Database Indexing Strategies

Database Indexing Strategies

What Is Database Indexing?

A database index is a data structure that improves the speed of data retrieval operations on a table at the cost of additional writes and storage space. Think of it like a book's index: instead of flipping through every page to find a topic, you look up the topic in the index and go directly to the right page.

How Indexes Work

Without an index, the database performs a sequential scan, reading every row until it finds matches. With an index, the database navigates a balanced tree structure to locate data in O(log n) time instead of O(n).

Sequential Scan: [Row1] [Row2] [Row3] ... [Row1M] = 1,000,000 reads

B-Tree Index: [Root] -> [Branch] -> [Leaf] -> [Row] = 3-4 reads

Index Types

B-Tree Index

The default and most common index type. Works well for equality and range queries.

CREATE INDEX idx_users_email ON users(email);

CREATE INDEX idx_users_created ON users(created_at);

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\-- Used for:

SELECT * FROM users WHERE email = '[e-mail]';

SELECT * FROM users WHERE created_at > '2026-01-01';

SELECT * FROM users WHERE email LIKE 'alice%';

Hash Index

Optimized for equality comparisons. Not suitable for range queries or sorting.

CREATE INDEX idx_sessions_token ON sessions USING HASH(session_token);

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\-- Good for:

SELECT * FROM sessions WHERE session_token = 'abc123';

GiST Index

Generalized Search Tree, useful for full-text search and geometric data.

CREATE INDEX idx_posts_content ON posts USING GIST(to_tsvector('english', content));

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\-- Used for:

SELECT * FROM posts

WHERE to_tsvector('english', content) @@ to_tsquery('database & indexing');

GIN Index

Generalized Inverted Index, optimized for composite types and arrays.

CREATE INDEX idx_article_tags ON articles USING GIN(tags);

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\-- Used for:

SELECT * FROM articles WHERE tags @> ARRAY['postgresql'];

SELECT * FROM articles WHERE tags && ARRAY['database', 'sql'];

BRIN Index

Block Range INdex, efficient for very large tables with naturally ordered data.

CREATE INDEX idx_logs_created ON logs USING BRIN(created_at)

WITH (pages_per_range = 32);

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\-- Best for:

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