Progress
Database Administration
Guide and Reference


Distributed Transactions Occurring Inconsistently

Two-phase commit ensures that distributed transactions (that is, single transactions involving multiple databases) occur consistently across all databases. Two-phase commit protects against inconsistencies by making sure that all databases commit the transaction, or that none commit. Two-phase commit is not necessary for transactions involving a single database. Table 6–7 provides examples.

Table 6–7: Reliability and Two-phase Commit 
If the Applications . . . 
Then . . .
Do not perform distributed transactions
Do not implement two-phase commit.
Perform distributed transactions and do not require consistency across databases
Do not implement two-phase commit.
Perform distributed transactions and require consistency across databases
Implement two-phase commit.


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