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From sangeetha s <sangee....@gmail.com>
Subject Re: problem while performing union on twotables
Date Sun, 20 Feb 2011 15:59:53 GMT
It is working perfectly after changing from union to union all.  Thanks to
all.


2011/2/19 Jov <zhao6014@gmail.com>

> if you want union,you should do it as this :
>
> select distinct ... from
> subquery1
> union all
> subquery2
>
> so,union = union distinct
> 在 2011-2-19 上午12:11,"sangeetha s" <sangee.sha@gmail.com>写道:
>
> > Hi,
> >
> > Thanks Jov and Ajo
> >
> > Changing from Union to Union all solved the issue. But do we need to
> specify
> > all the fields in the sub query?
> > Actually I had used the following query.
> >
> > INSERT OVERWRITE TABLE tab3 SELECT t3.col1,t3col2 FROM (SELECT id AS
> > col1,name AS col2 FROM tab1 UNION ALL SELECT id AS col1,name as col2 FROM
> > tab2)t3;
> >
> > The above query overwrite the result in the table tab3. If I am doing
> such
> > an operation in a table that has many fields,Is it necessary to specify
> all
> > the column names as a part of the sub query? If not, Will the query
> *SELECT
> > t3.* FROM (SELECT * FROM tab1 UNION ALL SELECT * FROM tab2)t3;* work?As I
> > am using this to update my table which has many columns,I need this.
> Well,I
> > will check it first and get back to you.
> >
> > Thank you,
> >
> >
> >
> > 2011/2/18 Jov <zhao6014@gmail.com>
> >
> >> hive0.4.1 do not support union,only support union all
> >> 在 2011-2-18 下午3:12,"sangeetha s" <sangee.sha@gmail.com>写道:
> >>
> >> >
> >> > Hi,
> >> >
> >> > I am trying to perform union of two tables which are having identical
> >> > schemas and distinct data.There are two tables 'oldtable' and
> 'newtable'.
> >> > The old table contains the information of old users and the new table
> >> will
> >> > conatin the information of new user. I am trying to update the new
> entry
> >> in
> >> > the old table using the following query.
> >> >
> >> > INSERT OVERWRITE TABLE oldtable SELECT * FROM (SELECT * FROM oldtable
> >> UNION
> >> > select * from newtable);
> >> >
> >> > executing the above query results,
> >> > FAILED:Parse Error:line 1.68 mismatched input 'select' expecting ALL
> in
> >> > query operator.
> >> >
> >> > I am currently using Hadoop verso 0.20.2 and Hive 0.4.1 from apache
> >> > disctribution. Will Hive 0.4.1 support UNION and UNION ALL queries? Is
> >> the
> >> > above problem is dueto the Hive version or due to a wrong query? Also
> I
> >> am
> >> > not using any partitions in these tables and the table format is
> >> TextFile.
> >> >
> >> > Any pointers in this regard would be highly helpful.
> >> >
> >> > --
> >> >
> >> >
> >> >
> >> > Regards,
> >> > Sangita
> >> >
> >> >
> >> > --
> >> >
> >>
> >
> >
> >
> > --
> >
> >
> >
> > Regards,
> > Sangita
>



-- 



Regards,
Sangita

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