Hi Andrey, thanks for response and little confused.
I hope "group" is the entries of two (or more) caches which are collocated with affinity key. please correct if i am wrong. "For example: In this case, we can make grouping and apply Having condition on map stage, that results in reducing network traffic." - *Agree. no aggregation in reduce and apply pagination and return to client ? or just return map response to client ?* Thanks. On 7 February 2017 at 14:55, Andrey Mashenkov <[email protected]> wrote: > Hi Anil, > > Group by queries with collocate = true will be correct if: > for every group there is only partition that contains all data of this > group. > Ignite does not know if group data is collocated for a query, so with this > option we can give a hint to Ignite. > > For example: In this case, we can make grouping and apply Having condition on > map stage, that > results in reducing network traffic. > > For non-collocated groups we can't apply Having on map stage as we have > only part of data at this time. > So, in this case with collocate = true we can get wrong results. > > > > On Tue, Feb 7, 2017 at 6:29 AM, Anil <[email protected]> wrote: > >> Hi, >> >> May I know what do you mean by "When used incorrectly" ? >> >> group by queries with collocate = true is not incorrect usage or i >> misunderstood this ? >> >> Thanks. >> >> On 7 February 2017 at 01:26, vkulichenko <[email protected]> >> wrote: >> >>> Well, I would agree that the flag is confusing, but your understanding >>> is not >>> correct. When used incorrectly, this flag does breaks query result >>> because >>> it forces Ignite to change execution plan to more optimal. This >>> optimization >>> doesn't always work though (that's actually the reason why it's >>> configurable). >>> >>> -Val >>> >>> >>> >>> -- >>> View this message in context: http://apache-ignite-users.705 >>> 18.x6.nabble.com/NOT-IN-in-ignite-tp9861p10458.html >>> Sent from the Apache Ignite Users mailing list archive at Nabble.com. >>> >> >> > > > -- > Best regards, > Andrey V. Mashenkov >
