Durability
ELI5 — The Vibe Check
Durability means once the database says 'committed', your data is saved forever — even if the server crashes right after. The database writes to disk before confirming success. It is the 'D' in ACID.
Real Talk
Durability guarantees that once a transaction has been committed, it will remain committed even in the event of system failure (power loss, crashes). This is achieved through write-ahead logging (WAL) where changes are written to a persistent log before being applied to data files.
When You'll Hear This
"Durability means committed data survives a server crash." / "Durability relies on write-ahead logging."
Related Terms
ACID (Atomicity, Consistency, Isolation, Durability)
ACID is the four guarantees a reliable database makes about transactions. It is the reason you trust a bank's database with your money.
Atomicity
Atomicity means a transaction is all-or-nothing — like an atom that cannot be split.
Consistency
Consistency in databases means a transaction can only bring the database from one valid state to another valid state.
Isolation
Isolation means concurrent transactions do not see each other's in-progress changes.
Transaction
A transaction groups multiple database operations into one all-or-nothing bundle. Either ALL of them succeed, or NONE of them happen.