The scatter property is being used to better distribute work across different worker shards. Prior to the scatter property, there were several incidents where work was unevenly distributed across tasks.
-- Ikai Lan Developer Programs Engineer, Google App Engine Blogger: http://googleappengine.blogspot.com Reddit: http://www.reddit.com/r/appengine Twitter: http://twitter.com/app_engine On Tue, Jan 11, 2011 at 11:06 AM, Stephen Johnson <[email protected]>wrote: > Thanks Ikai, > I've been using mapreduce for a long time and have never seen properties > added to our own entities like that. I'll take a look and see what it's > being used for so I understand it better and if this side-effect is > documented anywhere since it is strange and a little disconcerting to see > unknown properties popping up on your own entities. > Thanks, > Steve > > On Tue, Jan 11, 2011 at 11:42 AM, Ikai Lan (Google) < > [email protected] <ikai.l%[email protected]>> wrote: > >> It's a property used by the Mapper API: >> >> >> http://www.google.com/codesearch?q=__scatter__+package:http://appengine-mapreduce\.googlecode\.com&origq=__scatter__&btnG=Search+Trunk<http://www.google.com/codesearch?q=__scatter__+package:http://appengine-mapreduce%5C.googlecode%5C.com&origq=__scatter__&btnG=Search+Trunk> >> >> -- >> Ikai Lan >> Developer Programs Engineer, Google App Engine >> Blogger: http://googleappengine.blogspot.com >> Reddit: http://www.reddit.com/r/appengine >> Twitter: http://twitter.com/app_engine >> >> >> >> On Tue, Jan 11, 2011 at 9:32 AM, Stephen Johnson >> <[email protected]>wrote: >> >>> Checking my datastore statistics today I noticed that a new property >>> has magically appeared named __scatter__ of type ShortBlob. I don't >>> have any property defined with this name and it has the App Engine >>> format of __xyz__ naming so I'm assuming it's something Google has >>> introduced. However, this is a little disconcerting that it is showing >>> up in datastore statistics and no mention of this has been provided by >>> google. Also, it doesn't show up in the datastore viewere. Is anyone >>> else seeing this magic property? Should I be concerned? Anyone know >>> it's purpose? >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "Google App Engine" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]<google-appengine%[email protected]> >>> . >>> For more options, visit this group at >>> http://groups.google.com/group/google-appengine?hl=en. >>> >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "Google App Engine" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]<google-appengine%[email protected]> >> . >> For more options, visit this group at >> http://groups.google.com/group/google-appengine?hl=en. >> > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<google-appengine%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine?hl=en. > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
