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From Mich Talebzadeh <mich.talebza...@gmail.com>
Subject Re: Statistics collection in Phoenix
Date Wed, 02 Nov 2016 08:54:38 GMT
Thanks Sergey for clarification.

Regards

Dr Mich Talebzadeh



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On 2 November 2016 at 08:47, Sergey Soldatov <sergeysoldatov@gmail.com>
wrote:

> Hi Mich,
> The statistic is stored in SYSTEM.STATS table. And yes, there are
> guideposts per column family. As for (3) and (4) I think the answer is no.
> Guideposts are more like a point for specific row key (so if we scan for
> specific row key we can find quickly whether to start scanning) and let us
> run more scans in parallel. And they are using on client side.
>
> Thanks,
> Sergey
>
> On Sun, Oct 30, 2016 at 3:55 PM, Mich Talebzadeh <
> mich.talebzadeh@gmail.com> wrote:
>
>> According to document <https://phoenix.apache.org/update_statistics.html>
>>
>> The UPDATE STATISTICS command updates the statistics collected on a
>> table, to improve query performance. This command collects a set of keys
>> per region per column family that are equal byte distanced from each other.
>> These collected keys are called *guideposts* and they act as
>> *hints/guides* to improve the parallelization of queries on a given
>> target region.
>>
>> Few questions I Have
>>
>>
>>    1. Where are the statistics for a given table is kept
>>    2. Does this mean that each column family of  a table has its own
>>    statistics
>>    3. Is statistics collected similar to statistics for store-index in
>>    Hive ORC table
>>    4. Can statistics been used in predicate push down
>>
>>
>> Thanks
>>
>> Dr Mich Talebzadeh
>>
>>
>>
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>> *Disclaimer:* Use it at your own risk. Any and all responsibility for
>> any loss, damage or destruction of data or any other property which may
>> arise from relying on this email's technical content is explicitly
>> disclaimed. The author will in no case be liable for any monetary damages
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>>
>
>

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