From 2f1b23f61fa79aa1806dcb43cebb8b070a3f641c Mon Sep 17 00:00:00 2001
From: Andrew Lamb <andrew@nerdnetworks.org>
Date: Wed, 29 May 2024 16:45:06 -0400
Subject: [PATCH] reorganize

---
 .../examples/parquet_index_advanced.rs        | 98 ++++++++++++++-----
 1 file changed, 74 insertions(+), 24 deletions(-)

diff --git a/datafusion-examples/examples/parquet_index_advanced.rs b/datafusion-examples/examples/parquet_index_advanced.rs
index 370d6dc72fde..02966ab0ab51 100644
--- a/datafusion-examples/examples/parquet_index_advanced.rs
+++ b/datafusion-examples/examples/parquet_index_advanced.rs
@@ -46,7 +46,7 @@ use datafusion::physical_plan::ExecutionPlan;
 use datafusion::prelude::*;
 use datafusion_common::config::TableParquetOptions;
 use datafusion_common::{
-    internal_datafusion_err, DFSchema, DataFusionError, Result, ScalarValue,
+    internal_datafusion_err, internal_err, DFSchema, DataFusionError, Result, ScalarValue,
 };
 use datafusion_expr::utils::conjunction;
 use datafusion_expr::{TableProviderFilterPushDown, TableType};
@@ -259,27 +259,15 @@ impl TableProvider for IndexTableProvider {
         // Use the index to find the row groups that might have data that matches the
         // predicate. Any file that can not have data that matches the predicate
         // will not be returned.
-        let scan_builder = self.index.get_row_groups(predicate.clone())?;
-        let file_scan_config = scan_builder
-            .build(self.schema(), &self.dir)?
+        let exec = self
+            .index
+            .get_row_groups(predicate.clone())?
             .with_limit(limit)
-            .with_projection(projection.cloned());
+            .with_projection(projection.cloned())
+            .with_predicate(predicate)
+            .with_parquet_file_reader_factory(Arc::clone(&self.index.parquet_factory))
+            .build(self.schema(), &self.dir)?;
 
-        // build the actual parquet exec
-        let metadata_size_hint = None;
-        let table_parquet_options = TableParquetOptions::default();
-
-        // configure a Parquet opener that can provide the metadata for the
-        // files that are being scanned
-
-        // TODO make a builder for parquet exec
-        let exec = ParquetExec::new(
-            file_scan_config,
-            Some(predicate),
-            metadata_size_hint,
-            table_parquet_options,
-        )
-        .with_parquet_file_reader_factory(Arc::clone(&self.index.parquet_factory));
         Ok(Arc::new(exec))
     }
 
@@ -300,6 +288,16 @@ impl TableProvider for IndexTableProvider {
 struct ParquetScanBuilder {
     /// Files to scan. Use btree map for deterministic order
     files: BTreeMap<String, ScannedFile>,
+    /// Columns on which to project the data. Indexes that are higher than the
+    /// number of columns of `file_schema` refer to `table_partition_cols`.
+    projection: Option<Vec<usize>>,
+    /// The maximum number of records to read from this plan. If `None`,
+    /// all records after filtering are returned.
+    limit: Option<usize>,
+    /// Optional predicate for row filtering during parquet scan
+    predicate: Option<Arc<dyn PhysicalExpr>>,
+    /// user defined parquet file reader factory
+    parquet_file_reader_factory: Option<Arc<dyn ParquetFileReaderFactory>>,
 }
 
 impl ParquetScanBuilder {
@@ -319,18 +317,56 @@ impl ParquetScanBuilder {
         }
     }
 
+    /// Set the projection of the scan being built
+    pub fn with_projection(mut self, projection: Option<Vec<usize>>) -> Self {
+        self.projection = projection;
+        self
+    }
+    /// Set the limit of the scan being built
+    pub fn with_limit(mut self, limit: Option<usize>) -> Self {
+        self.limit = limit;
+        self
+    }
+
+    /// Set the predicate of the scan being built
+    pub fn with_predicate(mut self, predicate: Arc<dyn PhysicalExpr>) -> Self {
+        self.predicate = Some(predicate);
+        self
+    }
+
+    pub fn with_parquet_file_reader_factory(
+        mut self,
+        parquet_file_reader_factory: Arc<dyn ParquetFileReaderFactory>,
+    ) -> Self {
+        self.parquet_file_reader_factory = Some(parquet_file_reader_factory);
+        self
+    }
+
     /// Creates a ParquetExec that only scans the files and row groups specified in this builder
     ///
     /// # Parameters
     /// * `file_scan_config` - the base configuration for the scan (e.g. projection, limit)
     /// * `dir` - the directory containing the files
-    fn build(self, schema: SchemaRef, dir: &Path) -> Result<FileScanConfig> {
+    ///
+    /// # Returns
+    /// * a ParquetExec that scans only the files and row groups specified in this builder
+    fn build(self, schema: SchemaRef, dir: &Path) -> Result<ParquetExec> {
+        let Self {
+            files,
+            projection,
+            limit,
+            predicate,
+            parquet_file_reader_factory,
+        } = self;
+
         let object_store_url = ObjectStoreUrl::parse("file://")?;
-        let mut file_scan_config = FileScanConfig::new(object_store_url, schema);
+        let mut file_scan_config = FileScanConfig::new(object_store_url, schema)
+            .with_limit(limit)
+            .with_projection(projection);
 
         // Transform to the format needed to pass to ParquetExec
         // Create one file group per file (default to scanning them all in parallel)
-        for (file_name, scanned_file) in self.files {
+        for (file_name, scanned_file) in files {
             let ScannedFile {
                 file_size,
                 row_groups,
@@ -345,7 +381,21 @@ impl ParquetScanBuilder {
             ));
         }
 
-        Ok(file_scan_config)
+        let Some(parquet_file_reader_factory) = parquet_file_reader_factory else {
+            return internal_err!("Parquet file reader factory not set");
+        };
+
+        // build the actual parquet exec
+        let metadata_size_hint = None;
+        let table_parquet_options = TableParquetOptions::default();
+        let exec = ParquetExec::new(
+            file_scan_config,
+            predicate,
+            metadata_size_hint,
+            table_parquet_options,
+        )
+        .with_parquet_file_reader_factory(parquet_file_reader_factory);
+        Ok(exec)
     }
 }