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 <[email protected]>: > 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 <[email protected]>: > >> 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 <[email protected]>: >> >> > 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) >
