Re: Disable Adaptive encoding for Double and Float by default

Posted by Ajantha Bhat on
URL: http://apache-carbondata-dev-mailing-list-archive.168.s1.nabble.com/Disable-Adaptive-encoding-for-Double-and-Float-by-default-tp93914p93923.html

Hi Ravi, please find the performance readings below.

On TPCH 10GB data, carbon to carbon insert in on HDFS standalone cluster:

By disabling adaptive encoding for float and double.

insert is more than 10% faster [before 139 seconds, after this it is 114 seconds] and saves 25% memory in TLAB
store size has increased by 10% [before 2.3 GB, after this it is 2.55 GB]

Also we have below check. If data is more than 5 decimal precision. we don't apply adaptive encoding for double/float.

So, I am not sure how much it is useful for real-world double precision data.

Bottleneck is finding that decimal points from every float and double value [PrimitivePageStatsCollector.getDecimalCount(double)] 

where we convert to string and use substring().

so I want to disable adaptive encoding for double and float by default. 

 

Thanks,

Ajantha

On Wed, Mar 25, 2020 at 11:37 AM Ravindra Pesala <[hidden email]> wrote:

Hi ,

It increases the store size.  Can you give me performance figures with and
without these changes.  And also provide how much store size impact if we
disable it.


Regards,
Ravindra.

On Wed, 25 Mar 2020 at 1:51 PM, Ajantha Bhat <[hidden email]> wrote:

> Hi all,
>
> I have done insert into flow profiling using JMC with the latest code
> [with new optimized insert flow]
>
> It seems for *2.5GB* carbon to carbon insert, double and float stats
> collector has used *68.36 GB* [*25%* of TLAB (Thread local allocation
> buffer)]
>
> [image: Screenshot from 2020-03-25 11-18-04.png]
> *The problem is for every value of double and float in every row, we call *
> *PrimitivePageStatsCollector.getDecimalCount()**Which makes new objects
> every time.*
>
> So, I want to disable Adaptive encoding for float and double by default.
> *I will make this configurable.*
> If some user has a well-sorted double or float column and wants to apply
> adaptive encoding on that, they can enable it to reduce store size.
>
> Thanks,
> Ajantha
>
--
Thanks & Regards,
Ravi