Determine if the distributed database contains inconsistent data

If you determine that a transaction was inconsistently implemented, you must determine what this situation means for your distributed database system. Specifically, you must determine if data integrity has been affected.

A transaction that is inconsistently implemented causes problems whenever the piece of work rolled back by one participant is dependent on a piece of work that was updated by another participant. It is impossible to define these dependencies with SQL because distributed transactions do not support constraints that reference data at multiple database servers. The pieces of work are independent (no dependencies exist) only if the data could have been updated in two independent transactions. Otherwise, the pieces of work are considered to be dependent.

Before you proceed, consider the transaction that caused the error. Are the pieces of data that were updated and rolled back dependent on one another? Multiple updates might be included in a single transaction for reasons other than maintaining data integrity. For example, three possible reasons are as follows:
  • Reduced transaction overhead
  • Simplified coding
  • Programmer preference

Verify also that every participant database server that is assumed to have committed the transaction actually modified data. A read-only database server might be listed as a participant that committed a transaction.

If an inconsistent transaction does not lead to a violation of data integrity, you can quit the procedure at this point.


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