🎁 New User? Get 20% off your first purchase with code NEWUSER20 · ⚡ Instant download · 🔒 Secure checkout Register Now →
Menu

Categories

Databases Advanced

What is Deadlock?

A situation where two or more transactions permanently block each other by each holding locks that the other needs.

A deadlock occurs when Transaction A locks Row 1 and waits for Row 2, while Transaction B locks Row 2 and waits for Row 1. Neither can proceed. Databases detect deadlocks and abort one transaction to break the cycle.

Prevention strategies include consistent lock ordering (always lock resources in the same order), keeping transactions short, using appropriate isolation levels, and using SELECT FOR UPDATE SKIP LOCKED for queue patterns.

Related Terms

Database Constraint
Rules enforced by the database to maintain data integrity, including NOT NULL, UNIQUE, CHECK, PRIMARY KEY, and FOREIGN KEY.
View
A virtual table defined by a SQL query that provides a simplified or restricted view of data from one or more tables.
Migration
A version-controlled change to a database schema that can be applied and reversed systematically.
Database Proxy
A middleware server that sits between applications and databases, providing connection pooling, load balancing, and query routing.
Crosstab Query
A query that transforms rows into columns, creating a pivot table view of aggregated data.
Redis
An open-source, in-memory data store used as a database, cache, message broker, and queue with sub-millisecond response times.
 View All Databases Terms →