On Tue, May 8, 2018 at 9:25 AM, Saeid Sattari <[email protected]> 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
