Research Bret Slatkin Fan Out On Friday, February 7, 2014 1:43:33 PM UTC-8, Keith Lea wrote: > > Hi everyone, > > I'm a long time App Engine user for my app's backend, but I'm really still > a novice about the datastore. > > I'd like to add a new property (and index) for all entities of a certain > type. I have about 400,000 of this type of entity in the datastore, and I'd > like to load each one, add a property, and save it back to the datastore. > 400,000 times. > > This will obviously take a long time, so I'd really like to split it up > into ~100 tasks that each take 1/100th of the entities (~4,000 entities) > and perform this operation. > > But I really don't know how to do this using queries, and the Java > MapReduce library is overwhelmingly complicated. > > So how can I create 100 tasks that each take a unique chunk of the > entities to operate on? Is this called "sharding"? Is there a way for a > task to say "give me entity #200,000 thru #204,000"? (My entity's keys are > strings, which were generated by my application and generally look like > "928348-com.example-iOS".) > > I'm using Java and Objectify btw. Thanks for any help or guidance!! > > Keith >
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