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Summary

This is a summary of the decisions taken and conclusions made in the previous sections of this chapter:

• Transactions are atomic.
• Transactions are assumed to be operation level consistent. It is the programmers' responsibility to write them that way.
• Transactions are not guaranteed to be isolated, so additional locking may be required to guarantee system level consistency.
• Transactions are durable after having been committed on the server.
• Transactions that are pending seem committed to a client.
• Transactions cannot be nested.
• A new algorithm for optimistic concurrency control was sketched.
• Explicit begins and ends, and new transaction operations are needed.