[ as-id kuhm-plahy–uhnt] adj. ACID compliant refers to a set of properties in computer science that ensure database transactions are automatic, consistent, isolated, and durable; ACID stands for atomicity, consistency, isolation, and durability.
Atomicity: A transaction must be completed in its entirety or not at all. If a transaction aborts in the middle, all operations up to that point must be completely nullified.
Consistency: A transaction must transform a database from one consistent state to another consistent state. In other words, all data in a database must work as a state machine. The database must ensure all data is consistent at all times with all rules.
Isolation: Each transaction must occur independently of other transactions occurring at the same time. In other words, queries and transactions always run at a point in time. You can query data while many other users are changing data and you will not see their changes, and they will not see each other’s changes.
Durability: Committed transactions must be fully recoverable in all but the most extreme circumstances. Write-ahead logs provide absolute data durability until data is eventually written into permanent data and index files.
The ACID properties are intended to guarantee valid database transactions, even if there are network errors, disruptions, hardware failures, etc.