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From Tao Yan <t...@linkedin.com>
Subject Re: Difference between Select and Cube Select
Date Thu, 25 Aug 2016 17:02:07 GMT
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 <rajatgupta59@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 <tyan@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 <
>> rajatgupta59@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 <tyan@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 . <amareshwari@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 <tyan@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
>>>>>> tyan@linkedin.com
>>>>>> https://www.linkedin.com/in/taousc
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> *Tao Yan*
>>>> Software Engineer
>>>> Data Analytics Infrastructure Tools and Services
>>>>
>>>>
>>>>
>>>> 206.250.5345
>>>> tyan@linkedin.com
>>>> https://www.linkedin.com/in/taousc
>>>>
>>>
>>
>>
>> --
>>
>> *Tao Yan*
>> Software Engineer
>> Data Analytics Infrastructure Tools and Services
>>
>>
>>
>> 206.250.5345
>> tyan@linkedin.com
>> https://www.linkedin.com/in/taousc
>>
>


-- 

*Tao Yan*
Software Engineer
Data Analytics Infrastructure Tools and Services



206.250.5345
tyan@linkedin.com
https://www.linkedin.com/in/taousc

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