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Hive, mail # user - Enhancing Query Join to speed up Query


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Re: Enhancing Query Join to speed up Query
Navis류승우 2013-06-14, 01:42
You can use "explain" for confirming differences. For inner joins, it
would make the same plan.

2013/6/14 Igor Tatarinov <[EMAIL PROTECTED]>:
> I would expect no difference because of predicate pushdown.
>
> igor
> decide.com
>
>
> On Thu, Jun 13, 2013 at 11:31 AM, Naga Vijay <[EMAIL PROTECTED]> wrote:
>>
>> Sure, Will do
>>
>>
>> On Thu, Jun 13, 2013 at 10:42 AM, Stephen Sprague <[EMAIL PROTECTED]>
>> wrote:
>>>
>>> Hi naja,
>>> test those two versions (or three now) and report back to the group.  :)
>>> even if some smarty-pants thinks he knows the answer its always good to
>>> confirm things are as they should be.
>>>
>>>
>>> On Wed, Jun 12, 2013 at 11:54 PM, Sanjay Subramanian
>>> <[EMAIL PROTECTED]> wrote:
>>>>
>>>> Hi
>>>>
>>>> I would actually do it like this…so that the set on the left of JOIN
>>>> becomes smaller
>>>>
>>>> SELECT a.item_id, a.create_dt
>>>> FROM
>>>>      ( SELECT
>>>>                     item_id, create_dt
>>>>       FROM
>>>>                     A
>>>>       WHERE
>>>>                    item_id = 'I001'
>>>>        AND
>>>>                   category_name = 'C001'
>>>>       )  a
>>>> JOIN
>>>>          b
>>>> ON
>>>>         a.item_id = b.item_id
>>>> ;
>>>>
>>>>
>>>> From: Naga Vijay <[EMAIL PROTECTED]>
>>>> Reply-To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
>>>> Date: Wednesday, June 12, 2013 9:17 PM
>>>> To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
>>>> Subject: Enhancing Query Join to speed up Query
>>>>
>>>> Hi,
>>>>
>>>> Which of the two query options is better?
>>>>
>>>> SELECT a.item_id, a.create_dt
>>>> FROM   a JOIN b
>>>> ON     (a.item_id = b.item_id)
>>>> WHERE  a.item_id = 'I001'
>>>> AND    a.category_name = 'C001';
>>>>
>>>> - or -
>>>>
>>>> SELECT a.item_id, a.create_dt
>>>> FROM   a JOIN b
>>>> ON     (a.item_id = b.item_id AND a.item_id = 'I001')
>>>> WHERE  a.category_name = 'C001';
>>>>
>>>> Thanks
>>>> Naga
>>>>
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>>
>