Hi Rahul,
I agree query hint is better. The syntax from Ravi is the same with Oracle,
which is more popular and acceptable I think...
Show Segments statement could remove 'For table', just 'show segments
[dbname].<tableName>'. It's simple and same style with show partition
statement...
Thanks,
Lionel Cao
On Mon, Oct 9, 2017 at 8:54 AM, Raghunandan S <
carbondatacontributi...@gmail.com> wrote:
> Query hint is a better option.
> Some down side in using this approach:
> User will have to modify all his query to accommodate this.
> This won't be session scope but rather query scope
> On Mon, 9 Oct 2017 at 2:36 AM, jarray <jarray...@163.com> wrote:
>
> > 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
> > >
> >
>
