update public api Statistics::max to return an option.

I first re-named the existing method to `max_unchecked` and made it
internal to the crate.

I then added a `pub max(&self) -> Opiton<&T>` method.

I figure we can first change the public API before deciding what to do
about internal usage.

Ref: #6093

parquet/src/arrow/arrow_reader/statistics.rs

@@ -137,18 +137,18 @@ make_stats_iterator!(
 );
 make_stats_iterator!(
     MaxBooleanStatsIterator,
-    max,
+    max_unchecked,
     ParquetStatistics::Boolean,
     bool
 );
 make_stats_iterator!(MinInt32StatsIterator, min_unchecked, ParquetStatistics::Int32, i32);
-make_stats_iterator!(MaxInt32StatsIterator, max, ParquetStatistics::Int32, i32);
+make_stats_iterator!(MaxInt32StatsIterator, max_unchecked, ParquetStatistics::Int32, i32);
 make_stats_iterator!(MinInt64StatsIterator, min_unchecked, ParquetStatistics::Int64, i64);
-make_stats_iterator!(MaxInt64StatsIterator, max, ParquetStatistics::Int64, i64);
+make_stats_iterator!(MaxInt64StatsIterator, max_unchecked, ParquetStatistics::Int64, i64);
 make_stats_iterator!(MinFloatStatsIterator, min_unchecked, ParquetStatistics::Float, f32);
-make_stats_iterator!(MaxFloatStatsIterator, max, ParquetStatistics::Float, f32);
+make_stats_iterator!(MaxFloatStatsIterator, max_unchecked, ParquetStatistics::Float, f32);
 make_stats_iterator!(MinDoubleStatsIterator, min_unchecked, ParquetStatistics::Double, f64);
-make_stats_iterator!(MaxDoubleStatsIterator, max, ParquetStatistics::Double, f64);
+make_stats_iterator!(MaxDoubleStatsIterator, max_unchecked, ParquetStatistics::Double, f64);
 make_stats_iterator!(
     MinByteArrayStatsIterator,
     min_bytes,
@@ -251,7 +251,7 @@ make_decimal_stats_iterator!(
 );
 make_decimal_stats_iterator!(
     MaxDecimal128StatsIterator,
-    max,
+    max_unchecked,
     max_bytes,
     i128,
     from_bytes_to_i128
@@ -265,7 +265,7 @@ make_decimal_stats_iterator!(
 );
 make_decimal_stats_iterator!(
     MaxDecimal256StatsIterator,
-    max,
+    max_unchecked,
     max_bytes,
     i256,
     from_bytes_to_i256

parquet/src/arrow/arrow_writer/mod.rs

@@ -2544,7 +2544,7 @@ mod tests {
                 assert!(stats.has_min_max_set());
                 if let Statistics::Int32(stats) = stats {
                     assert_eq!(*stats.min_unchecked() as u32, *src_slice.iter().min().unwrap());
-                    assert_eq!(*stats.max() as u32, *src_slice.iter().max().unwrap());
+                    assert_eq!(*stats.max_unchecked() as u32, *src_slice.iter().max().unwrap());
                 } else {
                     panic!("Statistics::Int32 missing")
                 }
@@ -2585,7 +2585,7 @@ mod tests {
                 assert!(stats.has_min_max_set());
                 if let Statistics::Int64(stats) = stats {
                     assert_eq!(*stats.min_unchecked() as u64, *src_slice.iter().min().unwrap());
-                    assert_eq!(*stats.max() as u64, *src_slice.iter().max().unwrap());
+                    assert_eq!(*stats.max_unchecked() as u64, *src_slice.iter().max().unwrap());
                 } else {
                     panic!("Statistics::Int64 missing")
                 }
@@ -3070,7 +3070,7 @@ mod tests {
         // Column chunk of column "a" should have chunk level statistics
         if let Statistics::ByteArray(byte_array_stats) = a_col.statistics().unwrap() {
             let min = byte_array_stats.min_unchecked();
-            let max = byte_array_stats.max();
+            let max = byte_array_stats.max_unchecked();
 
             assert_eq!(min.as_bytes(), &[b'a']);
             assert_eq!(max.as_bytes(), &[b'd']);
@@ -3142,7 +3142,7 @@ mod tests {
         // Column chunk of column "a" should have chunk level statistics
         if let Statistics::ByteArray(byte_array_stats) = a_col.statistics().unwrap() {
             let min = byte_array_stats.min_unchecked();
-            let max = byte_array_stats.max();
+            let max = byte_array_stats.max_unchecked();
 
             assert_eq!(min.as_bytes(), &[b'a']);
             assert_eq!(max.as_bytes(), &[b'd']);