In general wider rows take a bit longer to read, however different access patterns have different performance. I did some tests here http://www.slideshare.net/aaronmorton/cassandra-sf-2012-technical-deep-dive-query-performance and http://thelastpickle.com/2011/07/04/Cassandra-Query-Plans/
I would suggest 1MM cols is fine, if you get to 10MM cols per row you probably have gone too far. Remember the byte size of the row is also important; larger rows churn memory more and take longer to compact / repair. Hope that helps. ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 8/09/2012, at 11:05 AM, Data Craftsman 木匠 <database.crafts...@gmail.com> wrote: > Hello experts. > > Should I limit the number of rows per Composite Primary Key's leading column? > > I think it falls into the same wide row good practice for number of > columns per row for CQL 2.0, e.g. 10M or less. > > Any comments will be appreciated. > > -- > Thanks, > > Charlie (@mujiang) 木匠 > ======= > Data Architect Developer 汉唐 田园牧歌DBA > http://mujiang.blogspot.com
