Databases Intermediate

What is Transaction?

A sequence of database operations that are treated as a single unit — either all succeed or all are rolled back.

Transactions ensure data consistency through ACID properties: Atomicity (all or nothing), Consistency (valid state transitions), Isolation (concurrent transactions don't interfere), and Durability (committed data persists).

Commands include BEGIN/START TRANSACTION, COMMIT (save changes), and ROLLBACK (undo changes). Isolation levels (READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, SERIALIZABLE) balance consistency and performance.

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A pre-compiled SQL template that uses parameters instead of literal values, preventing SQL injection and improving performance.

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Different index structures (B-tree, Hash, GIN, GiST, BRIN) optimized for various query patterns and data types.

A PostgreSQL maintenance operation that reclaims storage from dead tuples and updates statistics for the query planner.

Materialized View

A database object that stores the precomputed result of a query, offering faster reads at the cost of periodic refresh.

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A technique that maintains a cache of database connections for reuse, reducing the overhead of creating new connections.

A set of four properties (Atomicity, Consistency, Isolation, Durability) that guarantee reliable database transactions.

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