Lecture 11. Transaction Serialization Methods

There are two basic approaches to transaction serialization — based on synchronization captures of database objects and the use of timestamps. The essence of both approaches is to detect transaction conflicts and eliminate them. Below we consider these approaches in relatively detail.

We first note that for each of the approaches there are two types - pessimistic and optimistic. When using pessimistic methods, focused on situations where conflicts arise frequently, conflicts are recognized and resolved immediately when they occur. Optimistic methods are based on the fact that the results of all database modification operations are stored in the working memory of transactions. The real modification of the database is made only at the stage of committing the transaction. At the same time, it is checked whether there are any conflicts with other transactions.

Next, we limit ourselves to considering the more common pessimistic varieties of transaction serialization methods. Pessimistic methods are relatively simply transformed into their own optimistic options.