Databases Intermediate

What is Index?

A data structure that improves the speed of data retrieval operations on database tables at the cost of additional storage.

Indexes work like a book index — they allow the database to find rows without scanning the entire table. Without an index, a query on a million-row table checks every row. With an index, it jumps directly to matching rows.

Types include B-tree (default, good for ranges), hash (exact matches), GIN (full-text search), and GiST (geometric data). Over-indexing slows down writes since indexes must be updated on every INSERT/UPDATE.

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