[GitHub] [arrow-rs] mapleFU commented on a diff in pull request #4389: Truncate Min/Max values in the Colum Index

["mapleFU (via GitHub)" <gi...@apache.org>]

mapleFU commented on code in PR #4389:
URL: https://github.com/apache/arrow-rs/pull/4389#discussion_r1223871421


##########
parquet/src/column/writer/mod.rs:
##########
@@ -683,6 +683,14 @@ impl<'a, E: ColumnValueEncoder> GenericColumnWriter<'a, E> {
             .append_row_count(self.page_metrics.num_buffered_rows as i64);
     }
 
+    fn truncate_minmax_value(&self, data: &[u8]) -> Vec<u8> {
+        if let Some(max_len) = self.props.minmax_value_truncate_len() {
+            data[0..usize::min(data.len(), max_len)].to_vec()

Review Comment:
   Because `"Truncated < Origin"`, I guess:
   1. I guess it's ok to get min truncated
   2. For maximum, would it provide bad result and harm pruning?



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