Hi Todd, Many thanks.
Beat, Saeid On Tue, May 8, 2018 at 7:28 PM, Todd Lipcon <t...@cloudera.com> wrote: > On Tue, May 8, 2018 at 9:25 AM, Saeid Sattari <saeid.satt...@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 >
