C/SIDE is data-version oriented, meaning that each time a write transaction is performed, a new version of the data in the database is created.
Working with data versions makes it possible for many users to access the database without interfering with each other.
Maintaining Read Consistency and Concurrency
The implications of the data-version approach are many; most important is that different applications may be reading different versions of the same database. These versions are snapshots of the database at the time when the application started to access the database. In this way the DBMS allows for concurrency while still maintaining read consistency. If the accesses involve only data retrieval and no changes, then the newest version will persist for all applications. There will be no new version until a write transaction is performed.
When you update the database, your modifications are private and only become public after you commit your updates. Your newly-committed updates plus the part of the database which was not modified make up the newest version.