INF: Two-Phase and Three-Phase Commit Information

 Last reviewed: April 25, 1997
Article ID: Q61653

The information in this article applies to: 

  - Microsoft SQL Server version 4.2 for OS/2

SUMMARY

The clearest explanation of two-phase and three-phase commits is in Ullman's "Baseball Database" book. The reference to this publication does not represent a recommendation by Microsoft to use this book as a database reference; however, the information regarding two-phase and three-phase commits is helpful to understand these concepts.

MORE INFORMATION

Two-phase commit is defined to be the following: 

   A participant commits when it knows that all other participants
   have voted to commit.
Three-phase commit is defined to be the following: 

   A participant commits when it knows that all other participants
   know that all participants have voted to commit.
The extra phase reduces the amount of time that locks must be held if a failure occurs. Any participant that had received a commit or abort message can respond to a "help-me" message from a participant that is unsure of the state of the transaction. It is not necessary to hold all the locks until the coordinator gets back up.

Additional query words:
Keywords : kbother SSrvServer
Version : 4.2
Platform : OS/2

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Last reviewed: April 25, 1997
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