Thanks guys for your answers. I really appreciate that. Anyway, in order to avoid other problems and performance issues, I changed the structure of my database so that I will be able to do the transactions I want. Unfortunately the fact that a transaction is limited to entities of the same entity group is a pretty annoying limitation. I hope they will fix that some day...
Thank you all. Cristian Babula On Thu, Oct 21, 2010 at 10:19 PM, Ian Marshall <ianmarshall...@gmail.com> wrote: > I guess that the limit is enormous. (That doesn't help you since you > want to actually know!) > > Of course, you can only add entities to your entity group at a certain > rate of transactions per unit time. This is a constraint on how the > number of entities in any given entity group increases over time. > > > On Oct 21, 5:31 pm, Didier Durand <durand.did...@gmail.com> wrote: >> Hi, >> >> 1 info that is important to reach the value for this max number (if >> it exists) is the size of the entities: the bigger they are, the >> faster you will occupy the bandwith between the BigTable server and >> the processing server. >> >> So, if you want to go fast, you have to spread entities among many >> servers: see the end of this paper to see the trade-offs >> ->http://labs.google.com/papers/bigtable.html >> >> didier >> >> On Oct 21, 5:00 pm, "nicanor.babula" <nicanor.bab...@gmail.com> wrote: >> >> > Thank you all for your responses. >> > @alesj >> > No, I am not confusing entity "group" with the actual entities stored >> > in the datastore. >> >> > @Ian Marshall >> > Actually no, because I already did that kind of analysis. >> >> > I have to use transactions in order to maintain data consistency and >> > therefore I have to define the right entity groups. I already thought >> > of a solution, just that I have read in the docs that is not >> > recommended to put too many entities in an entity group. So: What is >> > the number of child entities a parent entity can have, past which the >> > datastore becomes slow? Hundreds? Thousands? Millions? >> > I also understand that all entities in an entity group are stored on >> > the same node of the datastore's distributed system and therefore I >> > understand that if the number of entities an entity group has is too >> > big, the queries will become slow, because will be processed by a >> > single node. Right? >> > Again: Which is that number? >> >> > Thanks and sorry if I bored you with my long email. ;) >> >> > On 21 Ott, 14:59, Ian Marshall <ianmarshall...@gmail.com> wrote: >> >> > > How about my comments below? >> >> > >http://www.google.com/url?url=http://groups.google.com/g/f907f736/t/f... >> >> > > Do they help you? >> >> > > On Oct 20, 6:39 pm, "nicanor.babula" <nicanor.bab...@gmail.com> wrote: >> >> > > > Hi everbody, >> >> > > > I have a question regarding the datastore best-practices. >> >> > > > The appengine's official documentation says that is not a good >> > > > practice to put too many entities in the same entity group. What does >> > > > "too many" mean in this case? Hundreds? Thousands? Milions? >> >> > > > Thanks in advance, >> > > > Cristian Babula. >> >> > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to google-appengine-j...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- Cristian Babula -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
