About the performance of the query

We are currently in the process of implementing a new Vertica for the system upgrade.
There is a group of tables in the existing system that holds data as follows.
Table 01: Data as of 01/01/2020
Table 02: Data as of 12/01/2019
...
Table 13: Data as of 01/01/2019
(All the same table definition)

When using the data, the above tables are combined to obtain the data.

Now, the above tables have been merged into a single table and
I'm thinking of adding unique key to indicate the date.

From the point of view of those who are familiar with Vertica, which of the following methods can be expected to improve speed more?
Multiple tables, as at present.
Combine them into a single table.

We look forward to hearing from you.