Force computation of a database query

compute() stores results in a remote temporary table. collect() retrieves data into a local tibble. collapse() is slightly different: it doesn't force computation, but instead forces generation of the SQL query. This is sometimes needed to work around bugs in dplyr's SQL generation.

compute(x, name = random_table_name(), ...)

collect(x, ...)

collapse(x, ...)

Arguments

x	A tbl
name	Name of temporary table on database.
...	Other arguments passed on to methods

Details

All functions preserve grouping and ordering.

See also

copy_to(), the opposite of collect(): it takes a local data frame and uploads it to the remote source.

Examples

if (require(dbplyr)) {
  mtcars2 <- src_memdb() %>%
    copy_to(mtcars, name = "mtcars2-cc", overwrite = TRUE)

  remote <- mtcars2 %>%
    filter(cyl == 8) %>%
    select(mpg:drat)

  # Compute query and save in remote table
  compute(remote)

  # Compute query bring back to this session
  collect(remote)

  # Creates a fresh query based on the generated SQL
  collapse(remote)
}
#> Loading required package: dbplyr
#> 
#> Attaching package: ‘dbplyr’
#> The following objects are masked from ‘package:dplyr’:
#> 
#>     ident, sql
#> # Source:   SQL [?? x 5]
#> # Database: sqlite 3.30.1 [:memory:]
#>      mpg   cyl  disp    hp  drat
#>    <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  18.7     8  360    175  3.15
#>  2  14.3     8  360    245  3.21
#>  3  16.4     8  276.   180  3.07
#>  4  17.3     8  276.   180  3.07
#>  5  15.2     8  276.   180  3.07
#>  6  10.4     8  472    205  2.93
#>  7  10.4     8  460    215  3   
#>  8  14.7     8  440    230  3.23
#>  9  15.5     8  318    150  2.76
#> 10  15.2     8  304    150  3.15
#> # … with more rows