Hi,
Thanks Jordan.
I had explained incorrectly regarding the use of the constructed parent key.
So in the example of Foo and FooLog, I had meant to say:
Construct a fake parent key for FooLog: parent =
Key("FooLog",foo.key.id())
So a FooLog entity would be created with
parent = Key("FooLog", foo.key.id())
e.g. foolog = FooLog(parent=parent, some_prop="property")
Is it OK to use a parent key that doesn't exist?
Thanks
Rob
On Monday, May 15, 2017 at 10:08:23 PM UTC+2, Jordan (Cloud Platform
Support) wrote:
>
> An Entity Group consists of a root ancestor Entity
> <https://cloud.google.com/appengine/docs/standard/python/datastore/entities#Python_Ancestor_paths>,
>
> and all of its descendants. There is a write throughput of one transaction
> per second per Entity Group, where transactions on a given entity group are
> executed serially, one after another. If too many concurrent modifications
> are attempted on the same entity group, Datastore will return an error.
>
> Your code should properly handle failed transactions with an exponential
> backoff retry strategy
> <https://cloud.google.com/storage/docs/exponential-backoff> in order to
> retry the transaction. You can also initially write to Memcache
> <https://cloud.google.com/appengine/docs/standard/python/memcache/> before
> performing a transaction, as this will make the written results available
> immediately. Your reads would then first attempt a read from Memcache, and
> then fail directly to reading from the Datastore if the results are not
> cached.
>
> - Alternatively as you suggested, you can manually place the parent 'Foo'
> entity ID in a different custom property of 'FooLog' and 'FooAudit',
> forcing both 'FooLog' and 'FooAudit' to both become their own root entity
> (as they will no longer have a parent). This will in turn remove the entity
> group, and remove the write throughput limit. Note, this will of course
> remove the strong-consistency
> <https://cloud.google.com/datastore/docs/concepts/structuring_for_strong_consistency>
>
> benefits of entity groups.
>
>
>
>
>
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