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From Mario Pastorelli <mario.pastore...@teralytics.ch>
Subject Re: Feedback about techniques for tuning batch scanning for my problem
Date Fri, 20 May 2016 14:09:21 GMT
Machines have 32 cores shared between Accumulo and Spark. Each machine has
5 disks on which there is HDFS and that Accumulo can use. How many threads
I should used?

On Fri, May 20, 2016 at 3:49 PM, David Medinets <david.medinets@gmail.com>
wrote:

> How many cores are on your servers? There are several thread counts you
> can change. Even +1 thread per server counts at some point if you have
> enough servers in the cluster.
>
> On Fri, May 20, 2016 at 2:54 AM, Mario Pastorelli <
> mario.pastorelli@teralytics.ch> wrote:
>
>> You mean the BatchScanner number of threads? I've made it parametric and
>> usually I use 1 or 2 threads per tablet server. Going up doesn't seem to do
>> anything for the performance.
>>
>> On Thu, May 19, 2016 at 6:21 PM, David Medinets <david.medinets@gmail.com
>> > wrote:
>>
>>> Have you tuned thread counts?
>>> On May 19, 2016 11:08 AM, "Mario Pastorelli" <
>>> mario.pastorelli@teralytics.ch> wrote:
>>>
>>>> Hey people,
>>>> I'm trying to tune a bit the query performance to see how fast it can
>>>> go and I thought it would be great to have comments from the community. The
>>>> problem that I'm trying to solve in Accumulo is the following: we want to
>>>> store the entities that have been in a certain location in a certain day.
>>>> The location is a Long and the entity id is a Long. I want to be able to
>>>> scan ~1M of rows in few seconds, possibly less than one. Right now, I'm
>>>> doing the following things:
>>>>
>>>>    1. I'm using a sharding byte at the start of the rowId to keep the
>>>>    data in the same range distributed in the cluster
>>>>    2. all the records are encoded, one single record is composed by
>>>>       1. rowId: 1 shard byte + 3 bytes for the day
>>>>       2. column family: 8 byte for the long corresponding to the hash
>>>>       of the location
>>>>       3. column qualifier: 8 byte corresponding to the identifier of
>>>>       the entity
>>>>       4. value: 2 bytes for some additional information
>>>>    3. I use a batch scanner because I don't need sorting and it's
>>>>    faster
>>>>
>>>> As expected, it takes few seconds to scan 1M rows but now I'm wondering
>>>> if I can improve it. My ideas are the following:
>>>>
>>>>    1. set table.compaction.major.ration to 1 because I don't care
>>>>    about the ingestion performance and this should improve the query
>>>>    performance
>>>>    2. pre-split tables to match the number of servers and then use a
>>>>    byte of shard as first byte of the rowId. This should improve both writing
>>>>    and reading the data because both should work in parallel for what I
>>>>    understood
>>>>    3. enable bloom filter on the table
>>>>
>>>> Do you think those ideas make sense? Furthermore, I have two questions:
>>>>
>>>>    1. considering that a single entry is only 22 bytes but I'm going
>>>>    to scan ~1M records per query, do you think I should change the
>>>>    BatchScanner buffers somehow?
>>>>    2. anything else to improve the scan speed? Again, I don't care
>>>>    about the ingestion time
>>>>
>>>> Thanks for the help!
>>>>
>>>> --
>>>> Mario Pastorelli | TERALYTICS
>>>>
>>>> *software engineer*
>>>>
>>>> Teralytics AG | Zollstrasse 62 | 8005 Zurich | Switzerland
>>>> phone: +41794381682
>>>> email: mario.pastorelli@teralytics.ch
>>>> www.teralytics.net
>>>>
>>>> Company registration number: CH-020.3.037.709-7 | Trade register Canton
>>>> Zurich
>>>> Board of directors: Georg Polzer, Luciano Franceschina, Mark Schmitz,
>>>> Yann de Vries
>>>>
>>>> This e-mail message contains confidential information which is for the
>>>> sole attention and use of the intended recipient. Please notify us at once
>>>> if you think that it may not be intended for you and delete it immediately.
>>>>
>>>
>>
>>
>> --
>> Mario Pastorelli | TERALYTICS
>>
>> *software engineer*
>>
>> Teralytics AG | Zollstrasse 62 | 8005 Zurich | Switzerland
>> phone: +41794381682
>> email: mario.pastorelli@teralytics.ch
>> www.teralytics.net
>>
>> Company registration number: CH-020.3.037.709-7 | Trade register Canton
>> Zurich
>> Board of directors: Georg Polzer, Luciano Franceschina, Mark Schmitz,
>> Yann de Vries
>>
>> This e-mail message contains confidential information which is for the
>> sole attention and use of the intended recipient. Please notify us at once
>> if you think that it may not be intended for you and delete it immediately.
>>
>
>


-- 
Mario Pastorelli | TERALYTICS

*software engineer*

Teralytics AG | Zollstrasse 62 | 8005 Zurich | Switzerland
phone: +41794381682
email: mario.pastorelli@teralytics.ch
www.teralytics.net

Company registration number: CH-020.3.037.709-7 | Trade register Canton
Zurich
Board of directors: Georg Polzer, Luciano Franceschina, Mark Schmitz, Yann
de Vries

This e-mail message contains confidential information which is for the sole
attention and use of the intended recipient. Please notify us at once if
you think that it may not be intended for you and delete it immediately.

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