Nick Johnson
December 2009
This is one of a series of in-depth articles discussing App Engine's datastore. To see the other articles in the series, see Related links .
Inevitably, a very small percentage of datastore requests will result in errors. We are constantly working to minimize the occurrence of errors, but your application needs to be able to handle them when they do occur in order to present the best experience to users.
This article will explain why errors occur, and what you can do when they do, in order to minimize disruption to your users.
Note: If your app receives an exception when submitting a transaction, it does not always mean that the transaction failed.
You can receive the following exceptions in cases where transactions have been committed and eventually will be applied successfully:
-
In Python,
Timeout
,TransactionFailedError
, orInternalError