dm_get_all_pks() checks the
dm object for set primary keys and
returns the tables, the respective primary key columns and their classes.
A tibble with the following columns:
column name(s) of primary key.
Currently, keys consisting of more than one column are not supported.
This feature is planned for dm 0.2.0.
pk_cols column may contain vectors of length greater than one.
dm_nycflights13() %>% dm_get_all_pks()#> # A tibble: 3 x 2 #> table pk_col #> <chr> <keys> #> 1 airlines carrier #> 2 airports faa #> 3 planes tailnum