In my opinion, your biggest take away from this should be to avoid having a mega entity group and you do this by simply *not* having all the entities in question have the same parent. Or perhaps more pointedly, any parent at all. Unless there is a really strong case to put many thousands of entities in the same entity group, I just wouldn't do it. You can have transactions across entity groups now so if you need a transaction with a few entities you are OK. As you need to relate the entities, do that by some other means instead of a parent entity. For example, you could use a ndb.KeyProperty or possibly just an encoded string or something along those lines.
On Tuesday, August 13, 2013 7:59:52 AM UTC-5, Martin Trummer wrote: > > I'm a newbie to the AppEngine datastore and like to know how to best > design this use case: > there may be some time-series with huge amount of data: e.g. terra-bytes > for one time-series > the transacations > doc<https://developers.google.com/appengine/docs/java/datastore/transactions>says > about entity groups: > > - *"Every entity belongs to an entity group, a set of one or more > entities that can be manipulated in a single transaction."* > - *"every entity with a given root entity as an ancestor is in the > same entity group. All entities in a group are stored in the same > Datastore node."* > > so does that mean, that all the terra-bytes of data for the huge > time-series would end up *on one computer* somewhere in the AppEngine > network? > if so: > > - that's not a good idea, right? > - how to avoid it? should I split up the data in sections (e.g. per > month) where each section has it's own kind/entity group? > > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/google-appengine. For more options, visit https://groups.google.com/groups/opt_out.
