Thanks! Is there a general estimation algorithm for all drivers? Or developer needs to implement estimation algorithm for each new drivers he added?
On Thu, Aug 25, 2016 at 11:38 AM, Rajat Khandelwal <[email protected]> wrote: > All drivers are asked to estimate. In the process of estimation, a driver > can fail, which lens server takes to mean that this driver cannot run this > query. > > On Thu, Aug 25, 2016 at 10:32 PM Tao Yan <[email protected]> wrote: > >> If Lens find the table is not a cube/dimension and pass the query through >> to drivers, then, how does Lens decide which driver to use? What if the >> driver picked is not the right one? For example, a query contains hive UDF >> is passed through to a MySQL database. >> >> Thanks, >> >> On Wed, Aug 24, 2016 at 11:47 PM, Rajat Khandelwal < >> [email protected]> wrote: >> >>> That doesn't happen. One driver is picked to run the query. The drivers >>> bid by providing their estimate of cost for running this query. >>> >>> On Thu, Aug 25, 2016 at 1:47 AM Tao Yan <[email protected]> wrote: >>> >>>> If the query is executed in multiple drivers, and more than one drivers >>>> return the result, then, how does Lens decide which result to return to >>>> user? And if one driver return result before others, will Lens wait for >>>> other drivers? >>>> >>>> Thanks, >>>> >>>> On Wed, Aug 24, 2016 at 12:00 AM, Rajat Khandelwal < >>>> [email protected]> wrote: >>>> >>>>> Yes, it can be any standard sql. The logic in lens is to check the >>>>> from clause, and if the entity in the from-clause is either a cube or a >>>>> dimension, then treat it as cube query, and do the translation before >>>>> running this query. If it's not a cube or a dimension, it's treated as a >>>>> native query and all the drivers are forwarded this query as it is without >>>>> any translation. >>>>> >>>>> >>>>> On Wed, Aug 24, 2016 at 5:43 AM Tao Yan <[email protected]> wrote: >>>>> >>>>>> When using "select" (not "cube select"), can it be any standard SQL >>>>>> (not bounded to Lens QL)? >>>>>> >>>>>> Thanks! >>>>>> >>>>>> On Tue, Aug 23, 2016 at 4:57 PM, amareshwarisr . < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> cube select expects the from clause to be on cube/dimension. select >>>>>>> is the one in SQL. >>>>>>> >>>>>>> Going forward from 2.6 onwards, cube keyword is optional for >>>>>>> cube/dimension queries. >>>>>>> >>>>>>> Thanks >>>>>>> >>>>>>> On Wed, Aug 24, 2016 at 3:53 AM, Tao Yan <[email protected]> wrote: >>>>>>> >>>>>>>> Hi Lens Developer, >>>>>>>> >>>>>>>> I found the following example in https://github.com/apache/ >>>>>>>> lens/blob/master/lens-examples/src/main/resources/ >>>>>>>> dimension-queries.sql >>>>>>>> >>>>>>>> select * from (cube select sample_dim.name name1, sample_dim2_chain >>>>>>>> .name name2 from sample_dim where sample_dim.name !='first') a >>>>>>>> >>>>>>>> I tested "cube select * " and it didn't work, and the above example >>>>>>>> shows "select *". What is the difference between "select" and "cube >>>>>>>> select"? >>>>>>>> >>>>>>>> Thanks, >>>>>>>> -- >>>>>>>> >>>>>>>> *Tao Yan* >>>>>>>> Software Engineer >>>>>>>> Data Analytics Infrastructure Tools and Services >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> 206.250.5345 >>>>>>>> [email protected] >>>>>>>> https://www.linkedin.com/in/taousc >>>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> >>>>>> *Tao Yan* >>>>>> Software Engineer >>>>>> Data Analytics Infrastructure Tools and Services >>>>>> >>>>>> >>>>>> >>>>>> 206.250.5345 >>>>>> [email protected] >>>>>> https://www.linkedin.com/in/taousc >>>>>> >>>>> >>>> >>>> >>>> -- >>>> >>>> *Tao Yan* >>>> Software Engineer >>>> Data Analytics Infrastructure Tools and Services >>>> >>>> >>>> >>>> 206.250.5345 >>>> [email protected] >>>> https://www.linkedin.com/in/taousc >>>> >>> >> >> >> -- >> >> *Tao Yan* >> Software Engineer >> Data Analytics Infrastructure Tools and Services >> >> >> >> 206.250.5345 >> [email protected] >> https://www.linkedin.com/in/taousc >> > -- *Tao Yan* Software Engineer Data Analytics Infrastructure Tools and Services 206.250.5345 [email protected] https://www.linkedin.com/in/taousc
