yes, I will asume this overhead in rowKey 2016-12-02 9:58 GMT+01:00 Billy(Yiming) Liu <liuyiming....@gmail.com>:
> Using Joint Dimension for your 1:1 relation is the right design. > > 2016-12-02 0:21 GMT+08:00 Alberto Ramón <a.ramonporto...@gmail.com>: > >> Nice Liu >> >> We have some cases like >> DayWeekTXT , DayWeekID >> MonthTXT, MonthID >> >> small proposal: >> Can would be interesting create Derived with 1:1 relation, with support >> for filters and Group by >> >> 2016-12-01 11:55 GMT+01:00 Billy(Yiming) Liu <liuyiming....@gmail.com>: >> >>> The cost of joint dimension compared with extended column is you have >>> more columns in the HBase rowkey. It may harm the query performance. But >>> most time, joint dimension is still recommended, since the normal dimension >>> column supports much more functions than extended column, such as count(*). >>> >>> 2016-12-01 17:07 GMT+08:00 Alberto Ramón <a.ramonporto...@gmail.com>: >>> >>>> Hello >>>> I was preparing a email with related doubts: >>>> >>>> Some times we have derived dimensions with relation 1:1, examples: >>>> WeekDayID & WeekDayTxt >>>> MonthID & WeekTxt >>>> >>>> SOL1: Derived. ID as Host and Txt Extended >>>> PB: You can't filter / Group by Txt >>>> >>>> SOL2: Joint. Define tuples of ID & TXT >>>> Some PB/limitation? (I need test this option) >>>> >>>> 2016-12-01 0:35 GMT+01:00 Billy(Yiming) Liu <liuyiming....@gmail.com>: >>>> >>>>> Thanks, Alberto. The explanation is accurate. EXTENDED_COLUMN is only >>>>> used for representation, but not filtering or grouping which is done by >>>>> HOST_COLUMN. So EXTENDED_COLUMN is not a dimension, it works like a >>>>> key/value map against the HOST_COLUMN. >>>>> >>>>> If the value in EXTENDED_COLUMN is not long, you could just define two >>>>> dimensions with joint dimension setting, it has almost the same >>>>> performance >>>>> impact with EXTENDED_COLUMN which reduces one dimension, but better >>>>> understanding. >>>>> >>>>> 2016-11-30 19:00 GMT+08:00 Alberto Ramón <a.ramonporto...@gmail.com>: >>>>> >>>>>> This will help you >>>>>> http://kylin.apache.org/docs/howto/howto_optimize_cubes.html >>>>>> >>>>>> The idea is always, How I can reduce the number of Dimension ? >>>>>> If you reduce Dim, the time / resources to build the cube and final >>>>>> size of >>>>>> it decrease --> Its good >>>>>> >>>>>> An example can be DIM_Persons: Id_Person , Name, Surname, Address, >>>>>> ..... >>>>>> Id_Person can be HostColumn >>>>>> and other columns can be calculated from ID --> are Extended >>>>>> Column >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> 2016-11-30 11:35 GMT+01:00 仇同心 <qiutong...@jd.com>: >>>>>> >>>>>> > Hi ,all >>>>>> > I don’t understand the usage scenarios of EXTENDED_COLUMN,although >>>>>> I saw >>>>>> > this article “https://issues.apache.org/jira/browse/KYLIN-1313”. >>>>>> > What,s the means about parameters of “Host Column” and “Extended >>>>>> Column”? >>>>>> > Why use this expression,and what aspects of optimization that this >>>>>> > expression solved? >>>>>> > Can be combined with a SQL statement to explain? >>>>>> > >>>>>> > >>>>>> > Thanks~ >>>>>> > >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> With Warm regards >>>>> >>>>> Yiming Liu (刘一鸣) >>>>> >>>> >>>> >>> >>> >>> -- >>> With Warm regards >>> >>> Yiming Liu (刘一鸣) >>> >> >> > > > -- > With Warm regards > > Yiming Liu (刘一鸣) >
