nealrichardson commented on a change in pull request #11183:
URL: https://github.com/apache/arrow/pull/11183#discussion_r712621368
##########
File path: r/R/query-engine.R
##########
@@ -20,11 +20,36 @@ do_exec_plan <- function(.data) {
final_node <- plan$Build(.data)
tab <- plan$Run(final_node)
+ # If arrange() created $temp_columns, make sure to omit them from the result
+ # We can't currently handle this in the ExecPlan itself because sorting
+ # happens in the end (SinkNode) so nothing comes after it.
if (length(final_node$sort$temp_columns) > 0) {
- # If arrange() created $temp_columns, make sure to omit them from the
result
tab <- tab[, setdiff(names(tab), final_node$sort$temp_columns), drop =
FALSE]
}
+ if (ncol(tab)) {
+ # Apply any column metadata from the original schema, where appropriate
+ original_schema <- source_data(.data)$schema
+ # TODO: do we care about other (non-R) metadata preservation?
Review comment:
Actually, on 5.0:
```
new <- tab %>%
select(carat) %>%
compute()
new$metadata
$pandas
[1] "{\"index_columns\": [\"__index_level_0__\"], \"column_indexes\":
[{\"name\":
...
```
I still don't think this is necessarily meaningful--especially when you're
dealing with multiple files with potentially different metadata.
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