Without versioning, concurrent read and write operations could cause inconsistencies in the database. The table-level versioning provided by Sybase IQ prevents inconsistencies both by serializing transactions, and by making the table the version level.
Sybase IQ allows multiple writers to modify a table serially—that is, one after the other, never more than one at a time—while multiple readers continue to work on an original copy of the table. With this method, IQ takes on full responsibility for preventing inconsistencies.
While any transaction processing system is designed to ensure that the database remains consistent, the Sybase IQ approach means that users don't need to worry about placing their queries and updates in appropriate transactions. IQ begins and ends transactions automatically, and ensures that read and write operations do not interfere with each other.
