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From bharath vissapragada <bhara...@students.iiit.ac.in>
Subject Re: mergeJoinTree ??
Date Fri, 24 Dec 2010 07:01:25 GMT
Thanks for the help namit !

:)

On Fri, Dec 24, 2010 at 12:00 PM, Namit Jain <njain@fb.com> wrote:
> Yes
>
> Sent from my iPhone
>
> On Dec 23, 2010, at 8:02 PM, "bharath vissapragada" <bharathvissapragada1990@gmail.com
>  > wrote:
>
>> Hi,
>>
>> Thanks for the reply .
>>
>> This is the optimization of converting 2 MR jobs to a single MR job
>> right ? as we are using only a single join val per table.
>>
>> Thanks
>> Bharath.V
>> 4th year undergraduate,
>> IIIT Hyderabad,
>>
>> On Fri, Dec 24, 2010 at 12:22 AM, Namit Jain <njain@fb.com> wrote:
>>> The idea there is to merge the join trees.
>>>
>>> For eg. If the query is:
>>>
>>> Select * from
>>> T1 join T2 on T1.key = T2.key
>>> join T3 on T1.key = T3.key
>>> Where ...
>>>
>>>
>>> One join can have 3 inputs: T1, T2 and T3.
>>>
>>> mergeJoinTree() merges the 2 join operators (T1,T2) and (result of
>>> (T1,T2), T3)
>>> into a new join operator with 3 children (T1,T2,T3)
>>>
>>>
>>> On 12/23/10 4:24 AM, "bharath vissapragada"
>>> <bharathvissapragada1990@gmail.com> wrote:
>>>
>>>> Hi all,
>>>>
>>>>
>>>> Once the JoinTrees are created by the the semantic analyzer for a
>>>> query block , a function mergeJoinTree(qb) is called .
>>>> Can anyone tell me what it does ?
>>>>
>>>> Thanks in anticipation,
>>>> Bharath.V
>>>
>>>
>

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