kudu-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Todd Lipcon <t...@cloudera.com>
Subject Re: Column Compression and Encoding
Date Tue, 08 May 2018 16:28:50 GMT
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

Mime
View raw message