Is this high replication datastore or master slave?

http://code.google.com/appengine/articles/transaction_isolation.html

"In a 
Master/Slave<http://code.google.com/appengine/docs/python/datastore/overview.html>
datastore,
the entire transaction is almost always completely applied before the commit
returns."

"A request that looks up an updated entity by its key at a time after
Milestone A is guaranteed to see the latest version of that entity. "

The key here is the word "almost always". If you do a transactional get by
key, it *should* return the most updated entity. All gets in High
Replication are, by default, transactional, so interestingly enough, it's
more strongly consistent in this regard than master/slave.

Ikai Lan
Developer Programs Engineer, Google App Engine
Blog: http://googleappengine.blogspot.com
Twitter: http://twitter.com/app_engine
Reddit: http://www.reddit.com/r/appengine



On Fri, Apr 8, 2011 at 2:30 PM, Simon Knott <[email protected]> wrote:

> I've had experience which suggests otherwise :)
>
> I'm finding that very occasionally the entity returned by the read-by-key
> hasn't been updated yet.  I've got around it by just re-queuing the task,
> and the second time around the entity is always in the updated state.
>
> I must admit that I was quite surprised it was happening - at first I
> thought I must not have enqueued in the task in the transaction, but after
> checking I definitely am.
>
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