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From yanqing weng <wengyanq...@gmail.com>
Subject Re: elastic execution engine question
Date Fri, 01 Jul 2016 01:49:13 GMT
Cool, your help is greatly appreciated.

On Fri, Jul 1, 2016 at 9:43 AM, Hubert Zhang <hzhang@pivotal.io> wrote:

> 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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