dbplyr and SQLite - are queries executed one after the other?

[doubledown]

When using the dbplyr package to talk to a sqlite database found here:

dbplyr docs

It mentions that "All dplyr calls are evaluated lazily, generating SQL that is only sent to the database when you request the data."

So within the example that they gave available :

# lazily generates query
summary <- mtcars2 %>% 
  group_by(cyl) %>% 
  summarise(mpg = mean(mpg, na.rm = TRUE)) %>% 
  arrange(desc(mpg))

# see query
summary %>% show_query()
#> <SQL>
#> SELECT `cyl`, AVG(`mpg`) AS `mpg`
#> FROM `mtcars`
#> GROUP BY `cyl`
#> ORDER BY `mpg` DESC

# execute query and retrieve results
summary %>% collect()
#> # A tibble: 3 x 2
#>     cyl   mpg
#>   <dbl> <dbl>
#> 1     4  26.7
#> 2     6  19.7
#> 3     8  15.1

I understand that the process is 1) summary object is the query() and 2) is only executed when you call the collect() function because it works on lazy execution.

what i would like to know is - is it possible to not write a string of queries and then collect them at the end for example?

# lazily generates query
summary <- mtcars2 %>% 
  group_by(cyl) %>% 
  summarise(mpg = mean(mpg, na.rm = TRUE)) %>% 
  arrange(desc(mpg))


summary_2 <- summary %>% nrow()




# execute query and retrieve results
summary_2 %>% collect()

Is this possible?

Or is the only option to write code - collect the code - send that table back to the database - perform another dplyr query - collect that and write that back to the database ?

Is the above the only process?