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From Hubert Zhang <hzh...@pivotal.io>
Subject Re: elastic execution engine question
Date Fri, 01 Jul 2016 01:43:50 GMT
You can try to the GUC

enforce_virtual_segment_number.

It works for queries without UDF.

On Fri, Jul 1, 2016 at 9:40 AM, yanqing weng <wengyanqing@gmail.com> wrote:

> Thanks Hubert.
>
> Can it be set only use one virtual segment for the query ? Because this
> can debug query more easily.
>
>
> On Fri, Jul 1, 2016 at 9:35 AM, Hubert Zhang <hzhang@pivotal.io> wrote:
>
>> For hash tables, The number of virtual segments is equal to the bucket
>> number of the table. Bucket number can be specified when creating the table.
>>
>> On Fri, Jul 1, 2016 at 9:31 AM, Ivan Weng <iweng@pivotal.io> wrote:
>>
>>> How about hash table?
>>>
>>> On Fri, Jul 1, 2016 at 9:30 AM, Hubert Zhang <hzhang@pivotal.io> wrote:
>>>
>>> > For random table, the virtual segment number is related to the data
>>> size of
>>> > the table. For large tables, we prefer use more virtual segments to
>>> achieve
>>> > better performance. While for small tables, less virtual segments are
>>> > needed, which could save resources and enable more concurrent queries.
>>>
>>> >
>>> > On Fri, Jul 1, 2016 at 9:22 AM, yanqing weng <wengyanqing@gmail.com>
>>> > wrote:
>>> >
>>> > > Hi HAWQ developer,
>>> > >
>>> > > Elastic execution engine is the important feature in HAWQ 2.0.
>>> > >
>>> > > I have a question for this feature in the HAWQ debugging. Is there
>>> > possible
>>> > > to control the virtual segment number when run query ? If so, which
>>> GUC
>>> > or
>>> > > parameter I should set ? Thanks.
>>> > >
>>> >
>>> >
>>> >
>>> > --
>>> > Thanks
>>> >
>>> > Hubert Zhang
>>> >
>>>
>>
>>
>>
>> --
>> Thanks
>>
>> Hubert Zhang
>>
>
>


-- 
Thanks

Hubert Zhang

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