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From sangeetha s <sangee....@gmail.com>
Subject Re: problem while performing union on twotables
Date Fri, 18 Feb 2011 16:10:16 GMT
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

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