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
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