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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.

Related Terms

Connection Pool
A cache of database connections that can be reused, avoiding the overhead of creating new connections for each request.
Trigger
A database object that automatically executes a specified function when certain events (INSERT, UPDATE, DELETE) occur on a table.
View
A virtual table defined by a SQL query that provides a simplified or restricted view of data from one or more tables.
Materialized View
A database object that stores the precomputed result of a query, offering faster reads at the cost of periodic refresh.
MVCC (Multi-Version Concurrency Control)
A technique where the database maintains multiple versions of data to allow concurrent reads and writes without locking.
Window Function
An SQL function that performs calculations across a set of rows related to the current row without collapsing the result set.
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