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Use any instead of for_each #15289

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Mar 21, 2025
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Use any instead of for_each #15289

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7 changes: 4 additions & 3 deletions datafusion/datasource-parquet/src/file_format.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -839,9 +839,10 @@ pub fn statistics_from_parquet_meta_calc(
total_byte_size += row_group_meta.total_byte_size() as usize;

if !has_statistics {
row_group_meta.columns().iter().for_each(|column| {
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@xudong963 xudong963 Mar 21, 2025

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The key issue is how has_statistics is assigned within the for_each loop. During iteration, the value of has_statistics is overwritten by each column's statistics status.

Example Scenario

Assume there are 2 columns with the following statistics status:

  • Column 1: Has statistics (statistics is Some)
  • Column 2: No statistics (statistics is None)

Execution process:

  • Processing Column 1: has_statistics becomes true
  • Processing Column 2: has_statistics becomes false

if the last column processed has no statistics, the final value of has_statistics would be false.

if the goal is to check "whether any column has statistics", a more suitable approach would be to use any

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@berkaysynnada berkaysynnada Mar 21, 2025

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You are right, I wasn't oppose to your change. I was just thinking a further refactor of unifying these two iterations:

  row_group_meta.columns().iter().for_each(|column| {
               has_statistics = column.statistics().is_some();
           });

and

      table_schema
          .fields()
          .iter()
          .enumerate()
          .for_each(|(idx, field)| {
          ...

but maybe not worth to try

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@xudong963 xudong963 Mar 21, 2025 •
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Yes, because even if a column in table_schema doesn't have the corresponding statistics in row_group_meta, it also may need to go summarize_min_max_null_counts to set statistics with null., I think it isn't worth trying.

In fact, I have tried it, and it doesn't make much sense, they (row_group_meta.columns() and table_schema.fields())are not always aligned.

has_statistics = column.statistics().is_some();
});
has_statistics = row_group_meta
.columns()
.iter()
.any(|column| column.statistics().is_some());
}
}
statistics.num_rows = Precision::Exact(num_rows);
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