redshift <- src_postgres(dbname = ...,
                         host = ...,
                         port = ...,
                         user = ...,
                         password = ...)

df <- tbl(redshift, "df")

df %>%
  ggplot(aes(duration)) + geom_histogram()

Error: ggplot2 doesn't know how to deal with data of class tbl_postgres/tbl_sql/tbl_lazy/tbl