Union all in Vertica SQL based on tables with different number of columns?

Question

Hellow i have two tables in Vertica SQL:

table 1

col1  col2  col3
1      3    5
2      4    6

table 2

col1  col2
11    33
22    44

And I would like to UNION these two tables, so as as result I would like to have:

col1  col2  col3
1      3     5
2      4     6
11     33    NULL
22     44    NULL

How can I do it in vertica

Answer 1

In general, you should use UNION ALL and define the extra column with whatever default value you want:

select col1, col2, col3
from table1
union all
select col1, col2, NULL as col3
from table2;

UNION incurs overhead for removing duplicates. In general, you should use UNION ALL unless you intend to remove duplicates.