Documentation for `arrange(random())`

[statzhero]

I was surprised to learn that the following arrange(random()) works as part of a query. But I couldn't find it in the documentation?

library(dplyr)
con <- DBI::dbConnect(duckdb::duckdb())
df <- tibble::tibble(id = 1:10, value = letters[1:10])
copy_to(con, df, "my_table")

tbl(con, "my_table") |>
  arrange(random()) |>
  collect()

[ejneer]

You've come across a very useful feature of dbplyr - namely that any function your R session doesn't know about is left as is (that is, it is left to the database to evaluate it). This is covered in the function translation vignette. In this case, you're using the duckdb function random because random is not an R function.

To drive the point home:

tbl(con, "my_table") |>
  arrange(an_unknown_function()) |>
  show_query()

# <SQL>
# SELECT my_table.*
# FROM my_table
# ORDER BY an_unknown_function()