Glossary

ACID

The four guarantees a transactional database makes: Atomicity, Consistency, Isolation, Durability.

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Definition

The four guarantees a transactional database makes: Atomicity, Consistency, Isolation, Durability.

How it works

Atomicity = all-or-nothing; Consistency = never violate invariants/constraints; Isolation = concurrent transactions don't see each other's half-done work; Durability = once committed, it survives a crash. SQL databases (Postgres, MySQL) are the classic ACID stores. The cost is that strict isolation + durability limit how far you can scale writes horizontally.

Common questions

What is ACID?

The four guarantees a transactional database makes: Atomicity, Consistency, Isolation, Durability.

How does ACID work?

Atomicity = all-or-nothing; Consistency = never violate invariants/constraints; Isolation = concurrent transactions don't see each other's half-done work; Durability = once committed, it survives a crash. SQL databases (Postgres, MySQL) are the classic ACID stores. The cost is…

What is ACID used for in system design?

Atomicity = all-or-nothing; Consistency = never violate invariants/constraints; Isolation = concurrent transactions don't see each other's half-done work; Durability = once committed, it survives a crash. SQL databases (Postgres, MySQL) are the classic ACID stores. The cost is…

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