feat: heuristic rule for fuse parquet dictionary page

src/query/expression/src/converts/arrow/mod.rs

@@ -14,6 +14,7 @@
 
 mod from;
 mod to;
+pub use self::to::table_schema_arrow_leaf_paths;
 
 pub const EXTENSION_KEY: &str = "Extension";
 pub const ARROW_EXT_TYPE_EMPTY_ARRAY: &str = "EmptyArray";

src/query/expression/src/converts/arrow/to.rs

@@ -41,6 +41,7 @@ use super::ARROW_EXT_TYPE_VARIANT;
 use super::ARROW_EXT_TYPE_VECTOR;
 use super::EXTENSION_KEY;
 use crate::infer_table_schema;
+use crate::schema::is_internal_column_id;
 use crate::types::DataType;
 use crate::types::DecimalColumn;
 use crate::types::DecimalDataType;
@@ -50,6 +51,7 @@ use crate::types::VectorColumn;
 use crate::types::VectorDataType;
 use crate::with_number_type;
 use crate::Column;
+use crate::ColumnId;
 use crate::DataBlock;
 use crate::DataField;
 use crate::DataSchema;
@@ -82,6 +84,57 @@ impl From<&TableSchema> for Schema {
     }
 }
 
+pub fn table_schema_arrow_leaf_paths(table_schema: &TableSchema) -> Vec<(ColumnId, Vec<String>)> {
+    let mut arrow_paths = Vec::new();
+    for field in table_schema.fields() {
+        if is_internal_column_id(field.column_id()) {
+            continue;
+        }
+
+        let arrow_field = Field::from(field);
+        let mut current_path = vec![arrow_field.name().clone()];
+        collect_arrow_leaf_paths(&arrow_field, &mut current_path, &mut arrow_paths);
+    }
+
+    let leaf_fields = table_schema.leaf_fields();
+    debug_assert_eq!(leaf_fields.len(), arrow_paths.len());
+
+    leaf_fields
+        .into_iter()
+        .zip(arrow_paths)
+        .map(|(field, path)| (field.column_id(), path))
+        .collect()
+}
+
+fn collect_arrow_leaf_paths(
+    arrow_field: &Field,
+    current_path: &mut Vec<String>,
+    paths: &mut Vec<Vec<String>>,
+) {
+    match arrow_field.data_type() {
+        ArrowDataType::Struct(children) => {
+            for child in children {
+                current_path.push(child.name().clone());
+                collect_arrow_leaf_paths(child.as_ref(), current_path, paths);
+                current_path.pop();
+            }
+        }
+        ArrowDataType::Map(child, _) => {
+            current_path.push(child.name().clone());
+            collect_arrow_leaf_paths(child.as_ref(), current_path, paths);
+            current_path.pop();
+        }
+        ArrowDataType::LargeList(child)
+        | ArrowDataType::List(child)
+        | ArrowDataType::FixedSizeList(child, _) => {
+            current_path.push(child.name().clone());
+            collect_arrow_leaf_paths(child.as_ref(), current_path, paths);
+            current_path.pop();
+        }
+        _ => paths.push(current_path.clone()),
+    }
+}
+
 impl From<&DataType> for ArrowDataType {
     fn from(ty: &DataType) -> Self {
         let fields = DataField::new("dummy", ty.clone());
@@ -93,7 +146,6 @@ impl From<&DataType> for ArrowDataType {
 impl From<&TableField> for Field {
     fn from(f: &TableField) -> Self {
         let mut metadata = HashMap::new();
-
         let ty = match &f.data_type {
             TableDataType::Null => ArrowDataType::Null,
             TableDataType::EmptyArray => {
@@ -264,6 +316,30 @@ impl DataBlock {
         self.to_record_batch(&table_schema)
     }
 
+    pub fn to_record_batch_with_arrow_schema(
+        self,
+        arrow_schema: &Arc<arrow_schema::Schema>,
+    ) -> Result<RecordBatch> {
+        let num_fields = arrow_schema.fields.len();
+        if self.columns().len() != num_fields {
+            return Err(ErrorCode::Internal(format!(
+                "The number of columns in the data block does not match the number of fields in the table schema, block_columns: {}, table_schema_fields: {}",
+                self.columns().len(),
+                num_fields,
+            )));
+        }
+
+        if num_fields == 0 {
+            return Ok(RecordBatch::try_new_with_options(
+                Arc::new(Schema::empty()),
+                vec![],
+                &RecordBatchOptions::default().with_row_count(Some(self.num_rows())),
+            )?);
+        }
+
+        self.build_record_batch(arrow_schema.clone())
+    }
+
     pub fn to_record_batch(self, table_schema: &TableSchema) -> Result<RecordBatch> {
         if self.columns().len() != table_schema.num_fields() {
             return Err(ErrorCode::Internal(format!(
@@ -282,14 +358,18 @@ impl DataBlock {
         }
 
         let arrow_schema = Schema::from(table_schema);
+        self.build_record_batch(Arc::new(arrow_schema))
+    }
+
+    fn build_record_batch(self, arrow_schema: Arc<arrow_schema::Schema>) -> Result<RecordBatch> {
         let mut arrays = Vec::with_capacity(self.columns().len());
         for (entry, arrow_field) in self.take_columns().into_iter().zip(arrow_schema.fields()) {
             let array = entry.to_column().maybe_gc().into_arrow_rs();
 
             // Adjust struct array names
             arrays.push(Self::adjust_nested_array(array, arrow_field.as_ref()));
         }
-        Ok(RecordBatch::try_new(Arc::new(arrow_schema), arrays)?)
+        Ok(RecordBatch::try_new(arrow_schema, arrays)?)
     }
 
     fn adjust_nested_array(array: Arc<dyn Array>, arrow_field: &Field) -> Arc<dyn Array> {

src/query/storages/common/blocks/src/parquet_rs.rs

@@ -15,17 +15,23 @@
 use std::sync::Arc;
 
 use databend_common_exception::Result;
+use databend_common_expression::converts::arrow::table_schema_arrow_leaf_paths;
+use databend_common_expression::ColumnId;
 use databend_common_expression::DataBlock;
 use databend_common_expression::TableSchema;
+use databend_storages_common_table_meta::meta::StatisticsOfColumns;
 use databend_storages_common_table_meta::table::TableCompression;
 use parquet::arrow::ArrowWriter;
 use parquet::basic::Encoding;
 use parquet::file::metadata::KeyValue;
 use parquet::file::properties::EnabledStatistics;
 use parquet::file::properties::WriterProperties;
-use parquet::file::properties::WriterPropertiesBuilder;
 use parquet::file::properties::WriterVersion;
 use parquet::format::FileMetaData;
+use parquet::schema::types::ColumnPath;
+
+/// Disable dictionary encoding once the NDV-to-row ratio is greater than this threshold.
+const HIGH_CARDINALITY_RATIO_THRESHOLD: f64 = 0.1;
 
 /// Serialize data blocks to parquet format.
 pub fn blocks_to_parquet(
@@ -35,16 +41,58 @@ pub fn blocks_to_parquet(
     compression: TableCompression,
     enable_dictionary: bool,
     metadata: Option<Vec<KeyValue>>,
+) -> Result<FileMetaData> {
+    blocks_to_parquet_with_stats(
+        table_schema,
+        blocks,
+        write_buffer,
+        compression,
+        enable_dictionary,
+        metadata,
+        None,
+    )
+}
+
+/// Serialize blocks while optionally tuning dictionary behavior via NDV statistics.
+///
+/// * `table_schema` - Logical schema used to build Arrow batches.
+/// * `blocks` - In-memory blocks that will be serialized into a single Parquet file.
+/// * `write_buffer` - Destination buffer that receives the serialized Parquet bytes.
+/// * `compression` - Compression algorithm specified by table-level settings.
+/// * `enable_dictionary` - Enables dictionary encoding globally before per-column overrides.
+/// * `metadata` - Additional user metadata embedded into the Parquet footer.
+/// * `column_stats` - Optional NDV stats from the first block, used to configure writer properties
+///   before ArrowWriter instantiation disables further changes.
+pub fn blocks_to_parquet_with_stats(
+    table_schema: &TableSchema,
+    blocks: Vec<DataBlock>,
+    write_buffer: &mut Vec<u8>,
+    compression: TableCompression,
+    enable_dictionary: bool,
+    metadata: Option<Vec<KeyValue>>,
+    column_stats: Option<&StatisticsOfColumns>,
 ) -> Result<FileMetaData> {
     assert!(!blocks.is_empty());
-    let builder = parquet_writer_properties_builder(compression, enable_dictionary, metadata);
 
-    let props = builder.build();
+    // Writer properties cannot be tweaked after ArrowWriter creation, so we mirror the behavior of
+    // the streaming writer and only rely on the first block's NDV (and row count) snapshot.
+    let num_rows = blocks[0].num_rows();
+    let arrow_schema = Arc::new(table_schema.into());
+
+    let props = build_parquet_writer_properties(
+        compression,
+        enable_dictionary,
+        column_stats,
+        metadata,
+        num_rows,
+        table_schema,
+    );
+
     let batches = blocks
         .into_iter()
-        .map(|block| block.to_record_batch(table_schema))
+        .map(|block| block.to_record_batch_with_arrow_schema(&arrow_schema))
         .collect::<Result<Vec<_>>>()?;
-    let arrow_schema = Arc::new(table_schema.into());
+
     let mut writer = ArrowWriter::try_new(write_buffer, arrow_schema, Some(props))?;
     for batch in batches {
         writer.write(&batch)?;
@@ -53,12 +101,16 @@ pub fn blocks_to_parquet(
     Ok(file_meta)
 }
 
-pub fn parquet_writer_properties_builder(
+/// Create writer properties, optionally disabling dictionaries for high-cardinality columns.
+pub fn build_parquet_writer_properties(
     compression: TableCompression,
     enable_dictionary: bool,
+    cols_stats: Option<impl NdvProvider>,
     metadata: Option<Vec<KeyValue>>,
-) -> WriterPropertiesBuilder {
-    let builder = WriterProperties::builder()
+    num_rows: usize,
+    table_schema: &TableSchema,
+) -> WriterProperties {
+    let mut builder = WriterProperties::builder()
         .set_compression(compression.into())
         // use `usize::MAX` to effectively limit the number of row groups to 1
         .set_max_row_group_size(usize::MAX)
@@ -68,10 +120,147 @@ pub fn parquet_writer_properties_builder(
         .set_key_value_metadata(metadata);
 
     if enable_dictionary {
-        builder
+        // Enable dictionary for all columns
+        builder = builder
             .set_writer_version(WriterVersion::PARQUET_2_0)
-            .set_dictionary_enabled(true)
+            .set_dictionary_enabled(true);
+        if let Some(cols_stats) = cols_stats {
+            // Disable dictionary of columns that have high cardinality
+            for (column_id, components) in table_schema_arrow_leaf_paths(table_schema) {
+                if let Some(ndv) = cols_stats.column_ndv(&column_id) {
+                    if num_rows > 0
+                        && (ndv as f64 / num_rows as f64) > HIGH_CARDINALITY_RATIO_THRESHOLD
+                    {
+                        builder = builder
+                            .set_column_dictionary_enabled(ColumnPath::from(components), false);
+                    }
+                }
+            }
+        }
+        builder.build()
     } else {
-        builder.set_dictionary_enabled(false)
+        builder.set_dictionary_enabled(false).build()
+    }
+}
+
+/// Provides per column NDV statistics
+pub trait NdvProvider {
+    fn column_ndv(&self, column_id: &ColumnId) -> Option<u64>;
+}
+
+impl NdvProvider for &StatisticsOfColumns {
+    fn column_ndv(&self, column_id: &ColumnId) -> Option<u64> {
+        self.get(column_id).and_then(|item| item.distinct_of_values)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use databend_common_expression::types::number::NumberDataType;
+    use databend_common_expression::TableDataType;
+    use databend_common_expression::TableField;
+
+    use super::*;
+
+    struct TestNdvProvider {
+        ndv: HashMap<ColumnId, u64>,
+    }
+
+    impl NdvProvider for TestNdvProvider {
+        fn column_ndv(&self, column_id: &ColumnId) -> Option<u64> {
+            self.ndv.get(column_id).copied()
+        }
+    }
+
+    fn sample_schema() -> TableSchema {
+        TableSchema::new(vec![
+            TableField::new("simple", TableDataType::Number(NumberDataType::Int32)),
+            TableField::new("nested", TableDataType::Tuple {
+                fields_name: vec!["leaf".to_string(), "arr".to_string()],
+                fields_type: vec![
+                    TableDataType::Number(NumberDataType::Int64),
+                    TableDataType::Array(Box::new(TableDataType::Number(NumberDataType::UInt64))),
+                ],
+            }),
+            TableField::new("no_stats", TableDataType::String),
+        ])
+    }
+
+    fn column_id(schema: &TableSchema, name: &str) -> ColumnId {
+        schema
+            .leaf_fields()
+            .into_iter()
+            .find(|field| field.name() == name)
+            .unwrap_or_else(|| panic!("missing field {}", name))
+            .column_id()
+    }
+
+    #[test]
+    fn test_build_parquet_writer_properties_handles_nested_leaves() {
+        let schema = sample_schema();
+
+        let mut ndv = HashMap::new();
+        ndv.insert(column_id(&schema, "simple"), 500);
+        ndv.insert(column_id(&schema, "nested:leaf"), 50);
+        ndv.insert(column_id(&schema, "nested:arr:0"), 400);
+
+        let column_paths: HashMap<ColumnId, ColumnPath> = table_schema_arrow_leaf_paths(&schema)
+            .into_iter()
+            .map(|(id, path)| (id, ColumnPath::from(path)))
+            .collect();
+
+        let props = build_parquet_writer_properties(
+            TableCompression::Zstd,
+            true,
+            Some(TestNdvProvider { ndv }),
+            None,
+            1000,
+            &schema,
+        );
+
+        assert!(
+            !props.dictionary_enabled(&column_paths[&column_id(&schema, "simple")]),
+            "high cardinality top-level column should disable dictionary"
+        );
+        assert!(
+            props.dictionary_enabled(&column_paths[&column_id(&schema, "nested:leaf")]),
+            "low cardinality nested column should keep dictionary"
+        );
+        assert!(
+            !props.dictionary_enabled(&column_paths[&column_id(&schema, "nested:arr:0")]),
+            "high cardinality nested array element should disable dictionary"
+        );
+        assert!(
+            props.dictionary_enabled(&column_paths[&column_id(&schema, "no_stats")]),
+            "columns without NDV stats keep the default dictionary behavior"
+        );
+    }
+
+    #[test]
+    fn test_build_parquet_writer_properties_disabled_globally() {
+        let schema = sample_schema();
+
+        let column_paths: HashMap<ColumnId, ColumnPath> = table_schema_arrow_leaf_paths(&schema)
+            .into_iter()
+            .map(|(id, path)| (id, ColumnPath::from(path)))
+            .collect();
+
+        let props = build_parquet_writer_properties(
+            TableCompression::Zstd,
+            false,
+            None::<TestNdvProvider>,
+            None,
+            1000,
+            &schema,
+        );
+
+        for field in schema.leaf_fields() {
+            assert!(
+                !props.dictionary_enabled(&column_paths[&field.column_id()]),
+                "dictionary must remain disabled when enable_dictionary is false",
+            );
+        }
     }
 }