asterixdb-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Riyafa Abdul Hameed <riy...@apache.org>
Subject Re: Creating aggregate functions
Date Mon, 17 Jul 2017 11:48:34 GMT
Hi again,

I think I can understand how to write the descriptor in the packages:
org.apache.asterix.runtime.aggregates.std and
org.apache.asterix.runtime.aggregates.scalar. But I am not sure I
understand how to write the descriptor in the package:
org.apache.asterix.runtime.aggregates.serializable.std  because it requires
setting a state in the init function that doesn't seem to have a pattern in
the other descriptors.
Also I don't seem to understand the reasons for implementing each of these
descriptors for the aggregate functions.

On 17 July 2017 at 16:56, Riyafa Abdul Hameed <riyafa.12@cse.mrt.ac.lk>
wrote:

> Hi all,
>
> I meant any explanation on the implementation of aggregate functions in
> AsterixDB would be highly appreciated.
>
> Thank you.
> Yours sincerely,
> Riyafa
>
> On 16 July 2017 at 08:01, Riyafa Abdul Hameed <riyafa@apache.org> wrote:
>
>> Dear all,
>>
>> I am trying to create aggregate functions and I see there are more than
>> one function descriptors for one single function.
>> For example the function array_count(collection) has the following
>> descriptors:
>>
>>
>>    - ScalarCountAggregateDescriptor
>>    - SerializableCountAggregateDescriptor
>>    - CountAggregateDescriptor
>>
>> I am not sure I understand the difference between each of this. Can you
>> please provide and example or point me to a documentation entry to learn
>> how to properly implement aggregate functions?
>>
>> The function I am trying to implement is ST_Extent.
>> <https://postgis.net/docs/manual-1.4/ST_Extent.html>
>>
>> Thank you.
>>
>> Yours sincerely,
>>
>> Riyafa
>>
>
>
>
> --
> Riyafa Abdul Hameed
> Undergraduate, University of Moratuwa
>
> Email: riyafa.12@cse.mrt.ac.lk
> Website: https://riyafa.wordpress.com/ <http://riyafa.wordpress.com/>
> <http://facebook.com/riyafa.ahf>  <http://lk.linkedin.com/in/riyafa>
> <http://twitter.com/Riyafa1>
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message