JasperSch opened a new issue #10809:
URL: https://github.com/apache/arrow/issues/10809
Hello,
When saving the result from `open_dataset()` to a variable, I get various
sporadic warning and error messages throughout the code that is executed
afterwards. It stops once I remove the variable.
The warnings/errors vary, but here some examples:
```
Error: Invalid <Schema>, external pointer to null
Warning message:
Number of rows unknown; returning NA
Error: IOError: Failed to open local file 'xxxx'. Detail: [Windows error 3]
The system cannot find the path specified.
```
Tested on following:
Ubuntu 20.04.2 LTS - R 3.6.3
Windows 10 - R 4.1.0.
Using arrow_4.0.1.
MWE:
```
library(arrow)
library(dplyr)
dir <- tempdir()
df <- mtcars
arrow::write_dataset(df, dir)
# Directly using the object returned by open_dataset gives no messages
result <- arrow::open_dataset(dir) %>%
collect()
1+1
# Leaving dataset open causes messages
result <- arrow::open_dataset(dir)
1+1
1+2
1+3
remove(result)
# No messages anymore
unlink(dir, recursive = TRUE)
```
Thanks in advance for your feedback and for maintaining such a great package.
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