Principles of Transaction Processing, 2nd Edition

Chapter 8

Two-Phase Commit

8.1 Introduction

The previous chapter showed how to use logging to ensure that a transaction is atomic with respect to failures, provided that the transaction updates data only in one resource manager. If two or more resource managers process updates for a transaction, then another technique is needed to ensure that the transaction commits at all resource managers or at none of them. This is called the two-phase commit protocol. Chapter 1 briefly introduced the protocol. This chapter develops it in more detail.

The main goal of the protocol is to ensure that a transaction either commits at all the resource managers that it accessed or aborts at all of them. The undesirable outcome that the protocol avoids is that the ...