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https://issues.apache.org/jira/browse/ARROW-15926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17508809#comment-17508809
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Nicola Crane commented on ARROW-15926:
--------------------------------------
I had a look into this, and although it is technically possible to pass the
convert_options parameter through like this, I don't think we actually support
that option with datasets. As [~paleolimbot] has said above, we should
definitely improve the error message here - I'll update the ticket to reflect
that.
> [R] CsvConvertOptions include_columns bug in open_dataset vs. read_csv_arrow
> ----------------------------------------------------------------------------
>
> Key: ARROW-15926
> URL: https://issues.apache.org/jira/browse/ARROW-15926
> Project: Apache Arrow
> Issue Type: Bug
> Components: R
> Affects Versions: 7.0.0
> Environment: Windows 10
> Reporter: Jameel Alsalam
> Priority: Minor
>
> I think there is a bug when reading a csv dataset where you don't want to
> read in all columns. As shown below, the identical code works in
> read_csv_arrow but errors in open_dataset. This can be worked around by
> reading in all columns and then selecting afterwards, but I am not sure if
> there is any performance advantage to omitting columns at the reading step.
>
> ``` r
> library(tidyverse)
> library(arrow)
> #>
> #> Attaching package: 'arrow'
> tmpf <- tempfile()
> dat <- tribble(
> ~key, ~val1,
> "A", "1",
> "B", "2",
> )
> write_csv(dat, tmpf)
> # works in read_csv_arrow, errors in open_dataset:
> read_csv_arrow(
> tmpf,
> convert_options = CsvConvertOptions$create(
> include_columns = "key"
> ))
> #> # A tibble: 2 x 1
> #> key
> #> <chr>
> #> 1 A
> #> 2 B
> open_dataset(
> tmpf, format = "csv",
> convert_options = CsvConvertOptions$create(
> include_columns = "key"
> )) %>% collect()
> #> Error in `handle_csv_read_error()`:
> #> ! Invalid: Multiple matches for FieldRef.Name(key) in key: [
> #> "A",
> #> "B"
> #> ]
> #> key: [
> #> "A",
> #> "B"
> #> ]
> # Note that it does work to select after open_dataset, thus not a blocking
> issue:
> open_dataset(tmpf, format = "csv") %>%
> select(key) %>%
> collect()
> #> # A tibble: 2 x 1
> #> key
> #> <chr>
> #> 1 A
> #> 2 B
> ```
> <sup>Created on 2022-03-12 by the [reprex
> package]([https://reprex.tidyverse.org|https://reprex.tidyverse.org/])
> (v2.0.1)</sup>
>
> I have tried this both with CRAN version 7 and the nightly version.
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