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From Vineet Goel <vg...@pivotal.io>
Subject Re: elastic execution engine question
Date Fri, 01 Jul 2016 04:48:54 GMT
What about hawq_rm_stmt_nvseg ?

http://hdb.docs.pivotal.io/20/reference/guc/parameter_definitions.html#hawq_rm_stmt_nvseg

-Vineet



On Jun 30, 2016, at 6:43 PM, 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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