[jira] [Created] (ARROW-16578) [R] unique() on a column of a tibble is much slower after writing to and reading from a parquet file

["Hideaki Hayashi (Jira)" <ji...@apache.org>]

Hideaki Hayashi created ARROW-16578:
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             Summary: [R] unique() on a column of a tibble is much slower after writing to and reading from a parquet file
                 Key: ARROW-16578
                 URL: https://issues.apache.org/jira/browse/ARROW-16578
             Project: Apache Arrow
          Issue Type: Bug
          Components: Parquet, R
    Affects Versions: 8.0.0, 7.0.0
            Reporter: Hideaki Hayashi


unique() on a column of a tibble is much slower after writing to and reading from a parquet file.

Here is a reprex.

{{df1 <- tibble::tibble(x=as.character(floor(runif(1000000) * 20)))}}
{{write_parquet(df1,"/tmp/test.parquet")}}
{{df2 <- read_parquet("/tmp/test.parquet")}}
{{system.time(unique(df1$x))}}
{{# Result on my late 2020 macbook pro with M1 processor:}}
{{#   user  system elapsed }}
{{#  0.020   0.000   0.021 }}
{{system.time(unique(df2$x))}}
{{#   user  system elapsed }}
{{#  5.230   0.419   5.649 }}

 

 



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