This result should tell you:
Query Rows Time of execution
w/o compression with compression with Columnar Indexes select * from warehouse.[dbo].[Timekeeper_Matter_Time_Summary_Period] 1,102,894 69 371
select * from warehouse.[dbo].Matter_Timekeeper_History 2,796,014 78 78 78
basically the query runs approximately 5.5 times longer with columnar index in one table and no improvement in the second one.
anybody have any clues as to where I should look?