perf: Remove cloning of ColumnChunkMetadata

crates/polars-parquet/src/parquet/metadata/column_chunk_metadata.rs

@@ -21,9 +21,12 @@ mod serde_types {
 use serde_types::*;
 
 /// Metadata for a column chunk.
-// This contains the `ColumnDescriptor` associated with the chunk so that deserializers have
-// access to the descriptor (e.g. physical, converted, logical).
-#[derive(Debug, Clone)]
+///
+/// This contains the `ColumnDescriptor` associated with the chunk so that deserializers have
+/// access to the descriptor (e.g. physical, converted, logical).
+///
+/// This struct is intentionally not `Clone`, as it is a huge struct.
+#[derive(Debug)]
 #[cfg_attr(feature = "serde_types", derive(Deserialize, Serialize))]
 pub struct ColumnChunkMetadata {
     #[cfg_attr(

crates/polars-parquet/src/parquet/metadata/file_metadata.rs

@@ -10,7 +10,7 @@ pub use crate::parquet::thrift_format::KeyValue;
 /// Metadata for a Parquet file.
 // This is almost equal to [`parquet_format_safe::FileMetaData`] but contains the descriptors,
 // which are crucial to deserialize pages.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct FileMetaData {
     /// version of this file.
     pub version: i32,
@@ -87,25 +87,6 @@ impl FileMetaData {
             column_orders,
         })
     }
-
-    /// Serializes itself to thrift's [`parquet_format_safe::FileMetaData`].
-    pub fn into_thrift(self) -> parquet_format_safe::FileMetaData {
-        parquet_format_safe::FileMetaData {
-            version: self.version,
-            schema: self.schema_descr.into_thrift(),
-            num_rows: self.num_rows as i64,
-            row_groups: self
-                .row_groups
-                .into_iter()
-                .map(|v| v.into_thrift())
-                .collect(),
-            key_value_metadata: self.key_value_metadata,
-            created_by: self.created_by,
-            column_orders: None, // todo
-            encryption_algorithm: None,
-            footer_signing_key_metadata: None,
-        }
-    }
 }
 
 /// Parses [`ColumnOrder`] from Thrift definition.

crates/polars-parquet/src/parquet/metadata/row_metadata.rs

@@ -1,3 +1,5 @@
+use std::sync::Arc;
+
 use hashbrown::hash_map::RawEntryMut;
 use parquet_format_safe::RowGroup;
 use polars_utils::aliases::{InitHashMaps, PlHashMap};
@@ -8,7 +10,6 @@ use polars_utils::unitvec;
 use super::column_chunk_metadata::{column_metadata_byte_range, ColumnChunkMetadata};
 use super::schema_descriptor::SchemaDescriptor;
 use crate::parquet::error::{ParquetError, ParquetResult};
-use crate::parquet::write::ColumnOffsetsMetadata;
 
 type ColumnLookup = PlHashMap<PlSmallStr, UnitVec<usize>>;
 
@@ -34,9 +35,8 @@ impl InitColumnLookup for ColumnLookup {
 
 /// Metadata for a row group.
 #[derive(Debug, Clone, Default)]
-// #[cfg_attr(feature = "serde_types", derive(serde::Deserialize, serde::Serialize))]
 pub struct RowGroupMetaData {
-    columns: Vec<ColumnChunkMetadata>,
+    columns: Arc<[ColumnChunkMetadata]>,
     column_lookup: PlHashMap<PlSmallStr, UnitVec<usize>>,
     num_rows: usize,
     total_byte_size: usize,
@@ -125,7 +125,7 @@ impl RowGroupMetaData {
 
                 Ok(column)
             })
-            .collect::<ParquetResult<Vec<_>>>()?;
+            .collect::<ParquetResult<Arc<[_]>>>()?;
 
         Ok(RowGroupMetaData {
             columns,
@@ -135,26 +135,4 @@ impl RowGroupMetaData {
             full_byte_range,
         })
     }
-
-    /// Method to convert to Thrift.
-    pub(crate) fn into_thrift(self) -> RowGroup {
-        let file_offset = self
-            .columns
-            .iter()
-            .map(|c| {
-                ColumnOffsetsMetadata::from_column_chunk_metadata(c).calc_row_group_file_offset()
-            })
-            .next()
-            .unwrap_or(None);
-        let total_compressed_size = Some(self.compressed_size() as i64);
-        RowGroup {
-            columns: self.columns.into_iter().map(|v| v.into_thrift()).collect(),
-            total_byte_size: self.total_byte_size as i64,
-            num_rows: self.num_rows as i64,
-            sorting_columns: None,
-            file_offset,
-            total_compressed_size,
-            ordinal: None,
-        }
-    }
 }

crates/polars-parquet/src/parquet/read/mod.rs

@@ -19,24 +19,7 @@ use polars_utils::mmap::MemReader;
 pub use stream::read_metadata as read_metadata_async;
 
 use crate::parquet::error::ParquetResult;
-use crate::parquet::metadata::{ColumnChunkMetadata, FileMetaData, RowGroupMetaData};
-
-/// Filters row group metadata to only those row groups,
-/// for which the predicate function returns true
-pub fn filter_row_groups(
-    metadata: &FileMetaData,
-    predicate: &dyn Fn(&RowGroupMetaData, usize) -> bool,
-) -> FileMetaData {
-    let mut filtered_row_groups = Vec::<RowGroupMetaData>::new();
-    for (i, row_group_metadata) in metadata.row_groups.iter().enumerate() {
-        if predicate(row_group_metadata, i) {
-            filtered_row_groups.push(row_group_metadata.clone());
-        }
-    }
-    let mut metadata = metadata.clone();
-    metadata.row_groups = filtered_row_groups;
-    metadata
-}
+use crate::parquet::metadata::ColumnChunkMetadata;
 
 /// Returns a new [`PageReader`] by seeking `reader` to the beginning of `column_chunk`.
 pub fn get_page_iterator(