same opinion with @Ravindra，use query hint is better approach ，the syntax is
easy to use
On 10/05/2017 17:10, Rahul Kumar wrote:
@Ravindra Thanks. Using query hint may be better approach.
I suggest following syntax :
*select * from t1 [in SEGMENTS(1,3,5)]; *
Thanks and Regards
* Rahul Kumar *
On Thu, Oct 5, 2017 at 1:04 PM, Ravindra Pesala <ravi.pes...@gmail.com>
wrote:
> Hi,
>
> Instead of using SET command to use for segments why don't you use QUERY
> HINT . Using query hint we can mention the segments inside the query itself
> as a hint.
>
> For example SELECT /*+SEGMENTS(1,3,5) */ from t1.
>
> By using the above custom hint we can query from selected segments only,
> This concept is supported in Spark also and this concept will be helpful in
> our any future optimizations
>
> Regards,
> Ravindra.
>
> On 5 October 2017 at 12:22, Rahul Kumar <rahul.ku...@knoldus.in> wrote:
>
> > @Jacky please find the reply of your doubts as follow :
> >
> >
> > *1. If user uses following command in two different beeline session,
> > will there be problem due to multithreading? SET
> > carbon.input.segments.default.*
> >
> > *carbontable=1,3,5; select * from carbontable; SET
> > carbon.input.segments.default.**carbontable=*;*
> >
> > *Ans: *In case of multithreading ,yes there will be problem.
> >
> > So threadSet() can be use to set the same property in multithread
> > mode.
> > * Folowing syntax can be used to set segment ids for multithread
> mode*
> > :
> > Syntax : CarbonSession.threadSet(“carbon.input.segments.<
> > databese_name>.<table_name>”,”<list
> > of segment ids>”)
> > e.g =>*future{*
> >
> > * CarbonSession.threadSet(“**carbon.input.segments.
> > default.carbontable”,”1,3,5”)*
> >
> > * sparkSession.sql(“select * from carbontable”).show*
> >
> > * CarbonSession.threadSet(“carbon.input.segments.
> > default.carbontable”,”*”)*
> >
> > * }*
> >
> > *Above will override the property at thread level. So property will be
> set
> > for each thread .*
> >
> >
> > *2. The RESET command is not clear, why this is needed? It seems SET
> > carbon.input.segments.default.**carbontable=* is enough, right? and what
> > parameter it has?*
> >
> > *Ans:* RESET command doesn't take any parameter. RESET is already
> > implemented behavior which resets all the properties to their default
> > value.So simillarly RESET query will set the above property also to its
> > default value.
> >
> > Thanks and Regards
> >
> > * Rahul Kumar *
> >
> >
> >
> > On Wed, Oct 4, 2017 at 7:21 PM, Jacky Li <jacky.li...@qq.com> wrote:
> >
> > > I have 2 doubts:
> > > 1. If user uses following command in two different beeline session,
> will
> > > there be problem due to multithreading?
> > > SET carbon.input.segments.default.carbontable=1,3,5;
> > > select * from carbontable;
> > > SET carbon.input.segments.default.carbontable=*;
> > >
> > >
> > > 2. The RESET command is not clear, why this is needed? It seems SET
> > > carbon.input.segments.default.carbontable=* is enough, right? and what
> > > parameter it has?
> > >
> > > Regards,
> > > Jacky
> > >
> > > > 在 2017年10月4日，上午12:42，Rahul Kumar <rahul.ku...@knoldus.in> 写道：
> > > >
> > > > <segmentReading.odt>
> > >
> > >
> >
>
>
>
> --
> Thanks & Regards,
> Ravi
>
