very very clear, thanks ¡¡ 2016-11-18 4:16 GMT+01:00 Li Yang <[email protected]>:
> For filter on derived column, it has to translate into a filter on PK. > > E.g. say USER_NAME is a derived column (not on cube), USER_ID is its PK > (on cube). When filter USER_NAME='liyang' comes in, it need to translate > into USER_ID in (1,211,382), where ID 1, 211, 382 are three users whose > name is 'liyang'. > > Now consider 'liyang' is so common a name that there are thousands of > 'liyang's. Then the IN clause becomes super long and can cause performance > problem during storage scanning. In such case, the filter can be translated > into a range filter instead, like USER_ID between 1 and 382. > > The threshold is used to decided whether the translation to return a IN > condition or a range condition. > > Cheers > Yang > > On Wed, Nov 16, 2016 at 12:35 AM, Alberto Ramón <[email protected] > > wrote: > >> About Kylin 2193 >> What is the poupose of >> org.apache.kylin.storage.translate.DerivedFilterTranslator# >> IN_THRESHOLD ? :) >> (when is used?) >> > >
