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From Saeid Sattari <saeid.satt...@gmail.com>
Subject Re: Column Compression and Encoding
Date Wed, 09 May 2018 06:25:02 GMT
Hi Todd,

Many thanks.

Beat,
Saeid

On Tue, May 8, 2018 at 7:28 PM, Todd Lipcon <todd@cloudera.com> wrote:

> On Tue, May 8, 2018 at 9:25 AM, Saeid Sattari <saeid.sattari@gmail.com>
> wrote:
>
>> Hi Todd,
>>
>> Thanks for these tips. Does compressing (LZ4,..) primary key's columns
>> cause performance loss?
>>
>
> If you have a composite primary key, Kudu already creates an internal
> combined column for their encoded concatenation. That internal column is
> already automatically compressed using PREFIX_ENCODING (because it's stored
> sorted, this is almost always a win) and using LZ4 (because there may be
> compressible patterns in non-prefix components of the composite key).
>
> So, if a column is part of the PK but not the entire PK, it will only be
> used on the read path when that actual column is selected, and it has the
> same performance impact (positive or negative) as any other column in the
> row.
>
> -Todd
>
> --
> Todd Lipcon
> Software Engineer, Cloudera
>

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