Hi ShaoFeng, Sure I'll do.
Best Regards, Hari On Sat, Oct 6, 2018 at 8:26 PM ShaoFeng Shi <[email protected]> wrote: > Hi Hari, > > Would you like to open a JIRA to Kylin with this? Thanks! > > hosur narahari <[email protected]> 于2018年10月6日周六 下午9:25写道： > >> Hi ShaoFeng, >> >> Exactly. It will solve the problem for all query engines whatsoever. >> >> Best Regards, >> Hari >> >> On Sat, Oct 6, 2018 at 6:51 PM ShaoFeng Shi <[email protected]> >> wrote: >> >>> Hi Hari, >>> >>> I see now; it is very similar to this integration with spark: >>> https://kylin.apache.org/docs/tutorial/spark.html >>> >>> Spark can register a SQL as a temp table, and then use that temp table >>> for subsequent analysis. But other engines may not have this function, so a >>> common view in Kylin may help to fill that gap, am I correct? >>> >>> >>> >>> hosur narahari <[email protected]> 于2018年10月2日周二 下午12:48写道： >>> >>>> Hi ShaoFeng, >>>> >>>> It could be either like lambda architecture or just like merging cube >>>> data with latest data for which cube has not yet been generated(in case of >>>> periodic cube generation). >>>> >>>> Now coming to aggregate pushdown. I'll give a very simple scenario. >>>> Consider below query. >>>> >>>> *Select sum(price) from kylin_sales* >>>> >>>> when we execute it in any query engine like presto, spark, drill etc., >>>> it doesn't execute above query but execute *Select price from >>>> kylin_sales.* After getting all price values, it does *map-reduce* to >>>> calculate sum. It's good for normal data sources but not for cube, since >>>> this is already pre-calculated. Even if in future aggregate pushdown is >>>> provided, it'll be very limited because we can't pushdown everything. For >>>> example, what do we do when we've joins and then aggregate. And AFAIK, >>>> unlike indexes(used for predicate pushdown), JDBC driver doesn't provide >>>> any information on pre aggregated data. >>>> >>>> How does views, solve this problem? >>>> >>>> Let's say we create view on above query like *Create view sum_view as >>>> Select sum(price) from kylin_sales;* >>>> >>>> In query engine we execute, *Select * from sum_view.* So kylin is >>>> queried for sum_view, which is basically *Select sum(price) from >>>> kylin_sales.* In this way, we can solve this problem using views. >>>> >>>> Please let me know, if I'm not being clear. >>>> >>>> Best Regards, >>>> Hari >>>> >>>> On Tue, Oct 2, 2018 at 8:52 AM ShaoFeng Shi <[email protected]> >>>> wrote: >>>> >>>>> Hi Hari, >>>>> >>>>> Sorry for the late response. Does it like a lambda architecture? How >>>>> can add a view to supporting aggregation pushdown? I'm not clear on this, >>>>> please elaborate. Thank you! >>>>> >>>>> hosur narahari <[email protected]> 于2018年9月30日周日 下午1:50写道： >>>>> >>>>>> Hi ShaoFeng, >>>>>> >>>>>> Is it possible to provide that support. Because, in many cases cubes >>>>>> are used with latest transaction data to get up to date analysis and some >>>>>> kind of query engine will be used for merging cube with non-cube data. >>>>>> And >>>>>> most of the query engines don't have aggregate pushdown, which makes it >>>>>> unable to query from cube. If we provide view, we can solve this problem >>>>>> for all query engines irrespective of whether they provide aggregate >>>>>> pushdown or not, making kylin more adaptable. >>>>>> >>>>>> Also it's just a conceptual view, not adding any overhead. >>>>>> >>>>>> Best Regards, >>>>>> Hari >>>>>> >>>>>> On Fri, Sep 28, 2018 at 7:40 PM ShaoFeng Shi <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> Hi Hari, >>>>>>> >>>>>>> Creating view on top of kylin tables is not supported in Kylin. >>>>>>> Kylin is read-only. >>>>>>> >>>>>>> hosur narahari <[email protected]> 于2018年9月28日周五 下午1:09写道： >>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> Is it possible to create views on the lines of rdbms or hive on top >>>>>>>> of kylin tables. >>>>>>>> >>>>>>>> Best Regards, >>>>>>>> Hari >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Best regards, >>>>>>> >>>>>>> Shaofeng Shi 史少锋 >>>>>>> >>>>>>> >>>>> >>>>> -- >>>>> Best regards, >>>>> >>>>> Shaofeng Shi 史少锋 >>>>> >>>>> >>> >>> -- >>> Best regards, >>> >>> Shaofeng Shi 史少锋 >>> >>> > > -- > Best regards, > > Shaofeng Shi 史少锋 > >
