fix: Parquet several smaller issues

crates/polars-arrow/src/offset.rs

@@ -518,6 +518,14 @@ impl<O: Offset> OffsetsBuffer<O> {
     pub fn into_inner(self) -> Buffer<O> {
         self.0
     }
+
+    /// Returns the offset difference between `start` and `end`.
+    #[inline]
+    pub fn delta(&self, start: usize, end: usize) -> usize {
+        assert!(start <= end);
+
+        (self.0[end + 1] - self.0[start]).to_usize()
+    }
 }
 
 impl From<&OffsetsBuffer<i32>> for OffsetsBuffer<i64> {

crates/polars-io/src/parquet/read/read_impl.rs

@@ -266,8 +266,8 @@ fn rg_to_dfs_prefiltered(
     // column indexes of the schema.
     let mut live_idx_to_col_idx = Vec::with_capacity(num_live_columns);
     let mut dead_idx_to_col_idx = Vec::with_capacity(num_dead_columns);
-    for (i, col) in file_metadata.schema().columns().iter().enumerate() {
-        if live_variables.contains(col.path_in_schema[0].deref()) {
+    for (i, field) in schema.fields.iter().enumerate() {
+        if live_variables.contains(&field.name[..]) {
             live_idx_to_col_idx.push(i);
         } else {
             dead_idx_to_col_idx.push(i);
@@ -406,22 +406,10 @@ fn rg_to_dfs_prefiltered(
             })
             .collect::<PolarsResult<Vec<_>>>()?;
 
-        let mut rearranged_schema: Schema = Schema::new();
-        if let Some(rc) = &row_index {
-            rearranged_schema.insert_at_index(
-                0,
-                SmartString::from(rc.name.deref()),
-                IdxType::get_dtype(),
-            )?;
-        }
-        for i in live_idx_to_col_idx.iter().copied() {
-            rearranged_schema.insert_at_index(
-                rearranged_schema.len(),
-                schema.fields[i].name.clone().into(),
-                schema.fields[i].data_type().into(),
-            )?;
-        }
-        rearranged_schema.merge(Schema::from(schema.as_ref()));
+        let Some(df) = dfs.first().map(|(_, df)| df) else {
+            return Ok(Vec::new());
+        };
+        let rearranged_schema = df.schema();
 
         rg_columns
             .par_chunks_exact_mut(num_dead_columns)
@@ -520,7 +508,7 @@ fn rg_to_dfs_optionally_par_over_columns(
         materialize_hive_partitions(&mut df, schema.as_ref(), hive_partition_columns, rg_slice.1);
         apply_predicate(&mut df, predicate, true)?;
 
-        *previous_row_count = previous_row_count.checked_add(current_row_count).ok_or(
+        *previous_row_count = previous_row_count.checked_add(current_row_count).ok_or_else(||
             polars_err!(
                 ComputeError: "Parquet file produces more than pow(2, 32) rows; \
                 consider compiling with polars-bigidx feature (polars-u64-idx package on python), \

crates/polars-parquet/src/arrow/read/deserialize/binary/basic.rs

@@ -144,6 +144,10 @@ impl<'a, 'b, O: Offset> BatchableCollector<(), Binary<O>> for DeltaCollector<'a,
         target.extend_constant(n);
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.decoder.skip_in_place(n)
+    }
 }
 
 impl<'a, 'b, O: Offset> BatchableCollector<(), Binary<O>> for DeltaBytesCollector<'a, 'b, O> {
@@ -159,6 +163,10 @@ impl<'a, 'b, O: Offset> BatchableCollector<(), Binary<O>> for DeltaBytesCollecto
         target.extend_constant(n);
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.decoder.skip_in_place(n)
+    }
 }
 
 impl<'a, O: Offset> StateTranslation<'a, BinaryDecoder<O>> for BinaryStateTranslation<'a> {

crates/polars-parquet/src/arrow/read/deserialize/binview.rs

@@ -319,6 +319,10 @@ impl<'a, 'b> BatchableCollector<(), MutableBinaryViewArray<[u8]>> for &mut Delta
         target.extend_constant(n, <Option<&[u8]>>::None);
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.decoder.skip_in_place(n)
+    }
 }
 
 impl<'a, 'b> DeltaCollector<'a, 'b> {
@@ -426,6 +430,10 @@ impl<'a, 'b> BatchableCollector<(), MutableBinaryViewArray<[u8]>> for DeltaBytes
         target.extend_constant(n, <Option<&[u8]>>::None);
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.decoder.skip_in_place(n)
+    }
 }
 
 impl utils::Decoder for BinViewDecoder {

crates/polars-parquet/src/arrow/read/deserialize/boolean.rs

@@ -165,6 +165,10 @@ impl<'a, 'b> BatchableCollector<u32, MutableBitmap> for BitmapCollector<'a, 'b>
         target.extend_constant(n, false);
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.0.skip_in_place(n)
+    }
 }
 
 impl ExactSize for (MutableBitmap, MutableBitmap) {

crates/polars-parquet/src/arrow/read/deserialize/dictionary.rs

@@ -191,6 +191,10 @@ impl<'a, 'b, K: DictionaryKey> BatchableCollector<(), Vec<K>> for DictArrayColle
         target.resize(target.len() + n, K::default());
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.values.skip_in_place(n)
+    }
 }
 
 impl<K: DictionaryKey> Translator<K> for DictArrayTranslator {

crates/polars-parquet/src/arrow/read/deserialize/fixed_size_binary.rs

@@ -16,6 +16,7 @@ pub(crate) enum StateTranslation<'a> {
     Dictionary(hybrid_rle::HybridRleDecoder<'a>, &'a Vec<u8>),
 }
 
+#[derive(Debug)]
 pub struct FixedSizeBinary {
     pub values: Vec<u8>,
     pub size: usize,
@@ -164,6 +165,12 @@ impl Decoder for BinaryDecoder {
                 target.resize(target.len() + n * self.size, 0);
                 Ok(())
             }
+
+            fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+                let n = usize::min(n, self.slice.len() / self.size);
+                *self.slice = &self.slice[n * self.size..];
+                Ok(())
+            }
         }
 
         let mut collector = FixedSizeBinaryCollector {

crates/polars-parquet/src/arrow/read/deserialize/nested.rs

@@ -202,6 +202,17 @@ pub fn columns_to_iter_recursive(
             )?
             .collect_n(filter)?
         },
+        Binary | Utf8 => {
+            init.push(InitNested::Primitive(field.is_nullable));
+            types.pop();
+            PageNestedDecoder::new(
+                columns.pop().unwrap(),
+                field.data_type().clone(),
+                binary::BinaryDecoder::<i32>::default(),
+                init,
+            )?
+            .collect_n(filter)?
+        },
         _ => match field.data_type().to_logical_type() {
             ArrowDataType::Dictionary(key_type, _, _) => {
                 init.push(InitNested::Primitive(field.is_nullable));

crates/polars-parquet/src/arrow/read/deserialize/nested_utils.rs

@@ -140,7 +140,7 @@ impl Nested {
 
     fn invalid_num_values(&self) -> usize {
         match &self.content {
-            NestedContent::Primitive => 0,
+            NestedContent::Primitive => 1,
             NestedContent::List { .. } => 0,
             NestedContent::FixedSizeList { width } => *width,
             NestedContent::Struct => 1,
@@ -204,6 +204,10 @@ impl<'a, 'b, 'c, D: utils::NestedDecoder> BatchableCollector<(), D::DecodedState
         self.decoder.push_n_nulls(self.state, target, n);
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.state.skip_in_place(n)
+    }
 }
 
 /// The initial info of nested data types.
@@ -290,6 +294,67 @@ impl NestedState {
     }
 }
 
+/// Calculate the number of leaf values that are covered by the first `limit` definition level
+/// values.
+fn limit_to_num_values(
+    def_iter: &HybridRleDecoder<'_>,
+    def_levels: &[u16],
+    limit: usize,
+) -> ParquetResult<usize> {
+    struct NumValuesGatherer {
+        leaf_def_level: u16,
+    }
+    struct NumValuesState {
+        num_values: usize,
+        length: usize,
+    }
+
+    impl HybridRleGatherer<u32> for NumValuesGatherer {
+        type Target = NumValuesState;
+
+        fn target_reserve(&self, _target: &mut Self::Target, _n: usize) {}
+
+        fn target_num_elements(&self, target: &Self::Target) -> usize {
+            target.length
+        }
+
+        fn hybridrle_to_target(&self, value: u32) -> ParquetResult<u32> {
+            Ok(value)
+        }
+
+        fn gather_one(&self, target: &mut Self::Target, value: u32) -> ParquetResult<()> {
+            target.num_values += usize::from(value == self.leaf_def_level as u32);
+            target.length += 1;
+            Ok(())
+        }
+
+        fn gather_repeated(
+            &self,
+            target: &mut Self::Target,
+            value: u32,
+            n: usize,
+        ) -> ParquetResult<()> {
+            target.num_values += n * usize::from(value == self.leaf_def_level as u32);
+            target.length += n;
+            Ok(())
+        }
+    }
+
+    let mut state = NumValuesState {
+        num_values: 0,
+        length: 0,
+    };
+    def_iter.clone().gather_n_into(
+        &mut state,
+        limit,
+        &NumValuesGatherer {
+            leaf_def_level: *def_levels.last().unwrap(),
+        },
+    )?;
+
+    Ok(state.num_values)
+}
+
 fn idx_to_limit(rep_iter: &HybridRleDecoder<'_>, idx: usize) -> ParquetResult<usize> {
     struct RowIdxOffsetGatherer;
     struct RowIdxOffsetState {
@@ -384,7 +449,7 @@ fn extend_offsets2<'a, D: utils::NestedDecoder>(
     >,
     nested: &mut [Nested],
     filter: Option<Filter>,
-    // Amortized allocations
+
     def_levels: &[u16],
     rep_levels: &[u16],
 ) -> PolarsResult<()> {
@@ -416,6 +481,9 @@ fn extend_offsets2<'a, D: utils::NestedDecoder>(
             if start > 0 {
                 let start_cell = idx_to_limit(&rep_iter, start)?;
 
+                let num_skipped_values = limit_to_num_values(&def_iter, def_levels, start_cell)?;
+                batched_collector.skip_in_place(num_skipped_values)?;
+
                 rep_iter.skip_in_place(start_cell)?;
                 def_iter.skip_in_place(start_cell)?;
             }
@@ -436,6 +504,8 @@ fn extend_offsets2<'a, D: utils::NestedDecoder>(
 
             // @NOTE: This is kind of unused
             let last_skip = def_iter.len();
+            let num_skipped_values = limit_to_num_values(&def_iter, def_levels, last_skip)?;
+            batched_collector.skip_in_place(num_skipped_values)?;
             rep_iter.skip_in_place(last_skip)?;
             def_iter.skip_in_place(last_skip)?;
 
@@ -447,6 +517,8 @@ fn extend_offsets2<'a, D: utils::NestedDecoder>(
                 let num_zeros = iter.take_leading_zeros();
                 if num_zeros > 0 {
                     let offset = idx_to_limit(&rep_iter, num_zeros)?;
+                    let num_skipped_values = limit_to_num_values(&def_iter, def_levels, offset)?;
+                    batched_collector.skip_in_place(num_skipped_values)?;
                     rep_iter.skip_in_place(offset)?;
                     def_iter.skip_in_place(offset)?;
                 }
@@ -601,23 +673,16 @@ fn extend_offsets_limited<'a, D: utils::NestedDecoder>(
                             }
                         }
 
-                        if embed_depth == max_depth - 1 {
-                            for _ in 0..num_elements {
-                                batched_collector.push_invalid();
-                            }
-
-                            break;
-                        }
-
                         let embed_num_values = embed_nest.invalid_num_values();
+                        num_elements *= embed_num_values;
 
                         if embed_num_values == 0 {
                             break;
                         }
-
-                        num_elements *= embed_num_values;
                     }
 
+                    batched_collector.push_n_invalids(num_elements);
+
                     break;
                 }
 

crates/polars-parquet/src/arrow/read/deserialize/null.rs

@@ -12,6 +12,7 @@ use crate::parquet::error::ParquetResult;
 use crate::parquet::page::{DataPage, DictPage};
 
 pub(crate) struct NullDecoder;
+#[derive(Debug)]
 pub(crate) struct NullArrayLength {
     length: usize,
 }

crates/polars-parquet/src/arrow/read/deserialize/primitive/basic.rs

@@ -147,6 +147,11 @@ where
         target.resize(target.len() + n, T::default());
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.chunks.skip_in_place(n);
+        Ok(())
+    }
 }
 
 #[allow(clippy::large_enum_variant)]
@@ -206,7 +211,7 @@ where
         }
 
         match self {
-            Self::Plain(t) => _ = t.nth(n - 1),
+            Self::Plain(t) => t.skip_in_place(n),
             Self::Dictionary(t) => t.values.skip_in_place(n)?,
             Self::ByteStreamSplit(t) => _ = t.iter_converted(|_| ()).nth(n - 1),
         }

crates/polars-parquet/src/arrow/read/deserialize/primitive/integer.rs

@@ -84,7 +84,7 @@ where
         }
 
         match self {
-            Self::Plain(v) => _ = v.nth(n - 1),
+            Self::Plain(v) => v.skip_in_place(n),
             Self::Dictionary(v) => v.values.skip_in_place(n)?,
             Self::ByteStreamSplit(v) => _ = v.iter_converted(|_| ()).nth(n - 1),
             Self::DeltaBinaryPacked(v) => v.skip_in_place(n)?,

crates/polars-parquet/src/arrow/read/deserialize/primitive/mod.rs

@@ -109,4 +109,8 @@ where
         target.resize(target.len() + n, T::default());
         Ok(())
     }
+
+    fn skip_in_place(&mut self, n: usize) -> ParquetResult<()> {
+        self.decoder.skip_in_place(n)
+    }
 }

crates/polars-parquet/src/arrow/read/deserialize/utils/array_chunks.rs

@@ -24,6 +24,11 @@ impl<'a, P: ParquetNativeType> ArrayChunks<'a, P> {
 
         Some(Self { bytes })
     }
+
+    pub(crate) fn skip_in_place(&mut self, n: usize) {
+        let n = usize::min(self.bytes.len(), n);
+        self.bytes = &self.bytes[n..];
+    }
 }
 
 impl<'a, P: ParquetNativeType> Iterator for ArrayChunks<'a, P> {
@@ -36,13 +41,6 @@ impl<'a, P: ParquetNativeType> Iterator for ArrayChunks<'a, P> {
         Some(item)
     }
 
-    #[inline(always)]
-    fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        let item = self.bytes.get(n)?;
-        self.bytes = &self.bytes[n + 1..];
-        Some(item)
-    }
-
     #[inline(always)]
     fn size_hint(&self) -> (usize, Option<usize>) {
         (self.bytes.len(), Some(self.bytes.len()))