Just found the thread that talks about needing the descending index for __key__ --- definitely seems like something that should be added to the documentation!
Ben On Jul 7, 12:56 pm, Ben Nevile <ben.nev...@gmail.com> wrote: > I have a job with 8 shards but only one of the shards is processing > any entities. Think this is related? > > mapreduce_id=159013376839436 > > Ben > > On Jun 16, 8:28 am, "Nick Johnson (Google)" <nick.john...@google.com> > wrote: > > > > > Hi Jason, > > > It's possible to do that right now. You simply need to define your own > > InputReader - see the existing ones for examples > > how:http://code.google.com/p/appengine-mapreduce/source/browse/trunk/pyth... > > > The best option is probably to extend the existing DatastoreInputReader, and > > override the split_input method. > > > -Nick Johnson > > > On Wed, Jun 16, 2010 at 4:17 PM, Jason C <jason.a.coll...@gmail.com> wrote: > > > Nick, > > > > It would be a great feature to allow us (developers) to define a > > > custom partitioning function for the shards - unless you guys have > > > some better magic in mind. > > > > It is very normal for us to see very poor distribution across our > > > shards in practise - in fact, we've only seen poor distributions. > > > > j > > > > On Jun 15, 8:04 am, "Nick Johnson (Google)" <nick.john...@google.com> > > > wrote: > > > > Hi Jason, > > > > > The current implementation of the datastore mapper uses lexicographical > > > > sharding over keys to assign datastore shards. Unfortunately, this can > > > lead > > > > to very inconsistent shard sizes, as you observe. > > > > > -Nick Johnson > > > > > On Fri, Jun 11, 2010 at 4:17 PM, Jason C <jason.a.coll...@gmail.com> > > > wrote: > > > > > We've been usingMapReducefor App Engine for a couple of different > > > > > jobs. > > > > > > Typically, we use 8 shards (the default), but it seems that only 3, > > > > > sometime 4, of the shards have any items in them? E.g., we're > > > > > currently running one job and three of the shards have >218,000 items > > > > > processed, but the other 5 shards appear to have zero. > > > > > > I can understand that a particular key distribution would have > > > > > different amounts in each shard, but with so many at zero, I suspect > > > > > there is something else happening? > > > > > > BTW, we have applied themapreduce-recommended __key__ DESC index, but > > > > > we still see this strange shard distribution. > > > > > > Is anyone else seeing this? > > > > > > j > > > > > > -- > > > > > You received this message because you are subscribed to the Google > > > Groups > > > > > "Google App Engine" group. > > > > > To post to this group, send email to google-appengine@googlegroups.com > > > . > > > > > To unsubscribe from this group, send email to > > > > > google-appengine+unsubscr...@googlegroups.com<google-appengine%2Bunsubscrib > > > > > e...@googlegroups.com><google-appengine%2Bunsubscrib > > > e...@googlegroups.com> > > > > > . > > > > > For more options, visit this group at > > > > >http://groups.google.com/group/google-appengine?hl=en. > > > > > -- > > > > Nick Johnson, Developer Programs Engineer, App Engine Google Ireland > > > > Ltd. > > > :: > > > > Registered in Dublin, Ireland, Registration Number: 368047 > > > > Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration > > > Number: > > > > 368047 > > > > -- > > > You received this message because you are subscribed to the Google Groups > > > "Google App Engine" group. > > > To post to this group, send email to google-appeng...@googlegroups.com. > > > To unsubscribe from this group, send email to > > > google-appengine+unsubscr...@googlegroups.com<google-appengine%2Bunsubscrib > > > e...@googlegroups.com> > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/google-appengine?hl=en. > > > -- > > Nick Johnson, Developer Programs Engineer, App Engine Google Ireland Ltd. :: > > Registered in Dublin, Ireland, Registration Number: 368047 > > Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration Number: > > 368047 -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appeng...@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
