Vertica performance on select from view with union
Vertica query performance depends highly on the predicate used in the query .

To get the gist of your performance , try getting the projection name of the selected columns of the query you are firing . The columns in the order by clause of the projection is very important in deciding the performance of your select. you can get that by running explain on your query .

Vertica improves performance by sorting the columns , compressing via encoding them so that they use minimal memory while running . 

Also run analyze_histogram(tablename, 100) on all your tables . this will ensure statistics over complete data sample, not just 10% of data sample which is taken by analyze_statistics .

Also , since you are doing union you should try to keep the sort order of all the projections same as after union it might be meaningless .