A simple denormalization is probably all that is called for - just merge the two tables into one (their union.) No need for this row type.
-- Jack Krupansky On Fri, Jan 8, 2016 at 9:30 AM, Jeff Jirsa <jeff.ji...@crowdstrike.com> wrote: > You’ll see better performance using a slice (which is effectively what > will happen if you put them into the same table and use query-1table-b), as > each node will only need to merge cells/results once. It may not be twice > as fast, but it’ll be fast enough to make it worthwhile. > > > > On 1/8/16, 12:13 AM, "Bamoqi" <bam...@gmail.com> wrote: > > >[Correction of the original message which contains typos in code.] > > > >Is it good for performance to put rows that are of different types but > >are always queried together in the same table partition? > > > >My consideration is that whether doing so will result in better > >memory/disk cache locality. > > > >Suppose I need to query for 2 different types of rows for a frequent > >user request, I can use 2 tables or 1 table: > > > >2 tables: > > > > create table t1( > > partitionkey int primary key, > > col1 int, col2 int, ... > > ) > > create table t2( > > partitionkey int primary key, > > col3 int, col4 int, ... > > ) > > > >query-2table: > > select col1,col2 from t1 where partitionkey = ? > > select col3,col4 from t2 where partitionkey = ? > > > >1 table: > > > > create table t( > > partitionkey int, > > rowtype tinyint, > > col1 int, col2 int, ... > > col3 int, col4 int, ... > > primary key( partitionkey, rowtype ) > > ) > > > >query-1table-a: > > select col1,col2 from t where partitionkey = ? and rowtype = 1 > > select col3,col4 from t where partitionkey = ? and rowtype = 2 > > > >or alternatively, query-1table-b: > > select rowtype,col1,col2,col3,col4 from t where partitionkey = ? > > // Used columns are `null`. Switch on `rowtype` in the app code > > > >Is there significant performance difference in query-2table, > >query-1table-a, query-1table-b? > >Is the cassandra client/coordinator smart enough to direct subsequent > >queries of the same (table, partitionkey) to the same node so they can > >reuse a cached page? > > > >Regards & Thanks >
