[R] show_exec_plan() for an arrow_dplyr_query

[asfimport]

{}Proposed approach{}: design doc

Steps

• Read about ExecPlan and ExecPlan::ToString

  • https://issues.apache.org/jira/browse/ARROW-14233
  • https://issues.apache.org/jira/browse/ARROW-15138
  • https://issues.apache.org/jira/browse/ARROW-13785

• Hook up to the existing C++ ToString method for ExecPlans

• Implement a ToString() method for ExecPlan R6 class

• Implement and document show_exec_plan()

  {}Original description{}:
  Now that we can print a query plan (ARROW-13785) we should wire this up in R so we can see what execution plans are being put together for various queries (like the TPC-H queries)

Reporter: Jonathan Keane / @jonkeane
Assignee: Dragoș Moldovan-Grünfeld / @dragosmg

Subtasks:

• [R] Read about ExecPlan and ExecPlan::ToString
• [R] Implement a $ToString() method for ExecPlan R6 class
• [R] Implement a print() method for the ExecPlan R6 class
• [R] Update print.arrow_dplyr_query
• [R] Implement show_arrow_query()
• [R][Doc] Document show_query() for arrow_dplyr_query

PRs and other links:

• GitHub Pull Request #13541

_{Note: This issue was originally created as ARROW-15016. Please see the migration documentation for further details.}

[asfimport]

Dewey Dunnington / @paleolimbot:
It seems like a route here would be to implement a ToString() and print() as R6 methods here:

arrow/r/R/dplyr.R

Line 91 in bd35629

print.arrow_dplyr_query <- function(x, ...) {

and here: https://github.com/apache/arrow/blob/master/r/src/compute-exec.cpp#L47

...and add a show_dplyr_query() function here (maybe like this):

library(arrow, warn.conflicts = FALSE)
library(dplyr, warn.conflicts = FALSE)

show_exec_plan <- function(.data) {
  adq <- arrow:::as_adq(.data)
  plan <- arrow:::ExecPlan$create()
  final_node <- plan$Build(.data)
  print(plan$ToString())
  invisible(.data)
}

ggplot2::mpg %>% 
  arrow_table() %>% 
  filter(year > 2007) %>% 
  show_exec_plan()
#> Error in print(plan$ToString()): attempt to apply non-function

Maybe here:

https://github.com/apache/arrow/blob/master/r/R/dplyr.R#L91

[asfimport]

Dewey Dunnington / @paleolimbot:
Issue resolved by pull request 13541
#13541