What best practices are recommended to optimize Vertica for a UI dashboard.
It depends the kind of query you'll run, but you want the data to be preprocessed (either using a datamart or specific LAP projections).
You'll probably want some partitioning (probably your dashboard in 2023 doesn't care much about anything pre-2020), and all your frequent filter must but the first ordered column of your relevant projections.
Those topics are quite well covered with our Vertica Academy Projection Tuning and Aggregate Projection Design certifications.
Please keep in mind that those certifications are free of charge and a lab is handed to you for five days to complete the trainings.