Transaction strategies

This chapter considers different transaction strategies regarding different correlation factors. Here, we suppose, that each sort of data state change runs in a transaction, which is the case for many DBMS implementations.

A2.1: A transaction is a set of database entries that has been updated or used in order to update database entries. Database entries stored within a transaction are visible for the process, that has started the transaction. After storing or rolling back a transaction, the database state is consistent.

In the first subtopic, a list of problems is described that arise, when running asynchronously (or non-serialized) transactions. The next subtopic lists a number of transaction strategies in order to avoid those problems. Both lists are not complete, but show how the database correlation factors influence transaction strategies.

The rules described in the following chapters are valid for different types of transactions. They apply on short and long internal transactions as well as on external or persistent transactions, which may take days or weeks. The intension of those rules is mainly to keep the database consistent without loosing much performance.