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Hive >> mail # user >> Indexes


Forgot to add to the previous email, HIVE-1644 added support to have
filters use indexes.

Thanks,
Shreepadma

On Tue, Oct 23, 2012 at 11:48 AM, Shreepadma Venugopalan <
[EMAIL PROTECTED]> wrote:

> Hi Peter,
>
> Indexing support was added to Hive in 0.7 and in 0.8 the query compiler
> was enhanced to optimized some class of queries (certain group bys and
> joins) using indexes. Assuming you are using the built in index handler you
> need to do the following _after_ you have created and rebuilt the index,
>
> SET hive.index.compact.file='/tmp/index_result';
> SET
> hive.input.format=org.apache.hadoop.hive.ql.index.compact.HiveCompactIndexInputFormat;
>
> You will then notice speed up for a query of the form,
>
> select count(*) from tab where indexed_col = some_val
>
> Thanks,
> Shreepadma
>
> On Tue, Oct 23, 2012 at 5:44 AM, Peter Marron <
> [EMAIL PROTECTED]> wrote:
>
>>  Hi,****
>>
>> ** **
>>
>> I’m very much a Hive newbie but I’ve been looking at HIVE-417 and this
>> page in particular:****
>>
>> http://cwiki.apache.org/confluence/display/Hive/IndexDev****
>>
>> Using this information I’ve been able to create an index (using Hive
>> 0.8.1)****
>>
>> and when I look at the contents it all looks very promising indeed.****
>>
>> However on the same page there’s this comment:****
>>
>> ** **
>>
>> “…This document currently only covers index creation and maintenance. A
>> follow-on will explain how indexes are used to optimize queries (building
>> on FilterPushdownDev<https://cwiki.apache.org/confluence/display/Hive/FilterPushdownDev>
>> )….”****
>>
>> ** **
>>
>> However I can’t find the “follow-on” which tells me how to exploit the
>> index that I’ve****
>>
>> created to “optimize” subsequent queries.****
>>
>> Now I’ve been told that I can create and use indexes with the current****
>>
>> release of Hive _*without*_ writing and developing any Java code of my
>> own.****
>>
>> Is this true? If so, how?****
>>
>> ** **
>>
>> Any help appreciated.****
>>
>> ** **
>>
>> Peter Marron.****
>>
>
>