What does ACID mean?
Practice this questionWANT TO UNDERSTAND THE CONCEPT FIRST?Learn ACID & transaction correctness
Definition:
ACID describes four properties used to reason about reliable transactions: atomicity, consistency, isolation and durability. Together they address partial changes, preserved rules, concurrent work and persistence after commit. They do not automatically supply correct business rules or the strongest isolation level.
Key points:
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Atomicity: all transaction changes succeed or none do.
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Consistency: declared rules remain valid; isolation: concurrent work has defined visibility.
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Durability: committed changes survive failures under the database's durability settings.
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For a transfer, debit and credit should commit together, while a constraint or application rule prevents an invalid balance.
Interview point:
- Database consistency in ACID means preserving defined invariants; it is not the same definition as consistency in CAP.
Adapted from 05_SQL_POSTGRESQL.md · “What does ACID mean?”. Code examples are study fragments. Difficulty and core labels are editorial estimates; version-specific behavior should be checked against your project.