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 <t...@linkedin.com> 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 <rajatgupt...@gmail.com > > 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 <t...@linkedin.com> 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 < >>> rajatgupt...@gmail.com> 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 <t...@linkedin.com> 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 . < >>>>> amareshw...@gmail.com> 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 <t...@linkedin.com> 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 >>>>>>> t...@linkedin.com >>>>>>> https://www.linkedin.com/in/taousc >>>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> -- >>>>> >>>>> *Tao Yan* >>>>> Software Engineer >>>>> Data Analytics Infrastructure Tools and Services >>>>> >>>>> >>>>> >>>>> 206.250.5345 >>>>> t...@linkedin.com >>>>> https://www.linkedin.com/in/taousc >>>>> >>>> >>> >>> >>> -- >>> >>> *Tao Yan* >>> Software Engineer >>> Data Analytics Infrastructure Tools and Services >>> >>> >>> >>> 206.250.5345 >>> t...@linkedin.com >>> https://www.linkedin.com/in/taousc >>> >> > > > -- > > *Tao Yan* > Software Engineer > Data Analytics Infrastructure Tools and Services > > > > 206.250.5345 > t...@linkedin.com > https://www.linkedin.com/in/taousc >
