Editing Database transaction (section)

==Object databases==
Relational databases are traditionally composed of tables with fixed-size fields and records. Object databases comprise variable-sized [[Binary large object|blobs]], possibly [[Serialization|serializable]] or incorporating a [[mime-type]]. The fundamental similarities between Relational and Object databases are the start and the [[Commit (data management)|commit]] or [[Rollback (data management)|rollback]].

After starting a transaction, database records or objects are locked, either read-only or read-write. Reads and writes can then occur. Once the transaction is fully defined, changes are committed or rolled back [[Atomicity (database systems)|atomically]], such that at the end of the transaction there is no [[Consistency (database systems)|inconsistency]].