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From Kristine Hahn <kh...@maprtech.com>
Subject Re: exec.queue.enable
Date Wed, 13 May 2015 22:26:15 GMT
Setting the large and small queue to 1 would'nt do it because the queues
could be operating simultaneously, says Dev. To serialize all incoming
queries, set the small queue at 0 and the exec.queue.threshold at 0.

Kristine Hahn
Sr. Technical Writer
415-497-8107 @krishahn


On Wed, May 13, 2015 at 2:51 PM, Richard Shaw <rshaw@maprtech.com> wrote:

> Thank you Kristine
>
> Please can you confirm the following would have the desired effect of
> completely serialising all incoming queries?
>
>     ALTER SYSTEM SET `exec.queue.enable`=true;
>     ALTER SYSTEM SET `exec.queue.small`=1;
>     ALTER SYSTEM SET `exec.queue.large`=1;
>
>
> Kind Regards,
> Richard
>
>
> On 30 April 2015 at 14:46, Kristine Hahn <khahn@maprtech.com> wrote:
>
>> Set options in sys.options to enable and manage query queuing, which is
>> turned off by default. There are two types of queues: large and small. You
>> configure a maximum number of queries that each queue allows by configuring
>> the following options in the sys.options table:
>>
>>    - exec.queue.large
>>    - exec.queue.small
>>
>> Example Configuration
>>
>> For example, you configure the queue reserved for large queries to hold a
>> 5-query maximum. You configure the queue reserved for small queue to hold
>> 20 queries. Users start to run queries, and Drill receives the following
>> query requests in this order:
>>
>>    - Query A (blue): 1 billion records, Drill estimates 10 million rows
>>    will be processed
>>    - Query B (red): 2 billion records, Drill estimates 20 million rows
>>    will be processed
>>    - Query C: 1 billion records
>>    - Query D: 100 records
>>
>> The exec.queue.threshold default is 30 million, which is the estimated
>> rows to be processed by the query. Queries A and B are queued in the large
>> queue. The estimated rows to be processed reaches the 30 million threshold,
>> filling the queue to capacity. The query C request arrives and goes on the
>> wait list, and then query D arrives. Query D is queued immediately in the
>> small queue because of its small size, as shown in the following diagram:
>>
>> [image: Inline image 1]
>>
>> The Drill queuing configuration in this example tends to give many users
>> running small queries a rapid response. Users running a large query might
>> experience some delay until an earlier-received large query returns and the
>> large queue is available to continue processing large queries.
>>
>> Kristine Hahn
>> Sr. Technical Writer
>> 415-497-8107 @krishahn
>>
>>
>> On Thu, Apr 30, 2015 at 12:04 AM, Richard Shaw <rshaw@maprtech.com>
>> wrote:
>>
>>> I'd like to better understand queuing, if it's in fact possible to
>>> serialise incoming queries, especially where I have a very small Drill
>>> installation with limited resources.
>>>
>>> Thank you
>>>
>>> Kind Regards,
>>> Richard
>>>
>>
>>
>

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