[BLAZE-808] Support statistics of ExecutionPlan for WindowExec

Author: SteNicholas

native-engine/datafusion-ext-plans/src/window_exec.rs

@@ -20,7 +20,7 @@ use arrow::{
     record_batch::{RecordBatch, RecordBatchOptions},
 };
 use datafusion::{
-    common::{Result, Statistics},
+    common::{stats::Precision, ColumnStatistics, Result, Statistics},
     execution::context::TaskContext,
     physical_expr::{EquivalenceProperties, PhysicalSortExpr},
     physical_plan::{
@@ -131,7 +131,19 @@ impl ExecutionPlan for WindowExec {
     }
 
     fn statistics(&self) -> Result<Statistics> {
-        todo!()
+        let input_stat = self.input.statistics()?;
+        let win_cols = self.context.window_exprs.len();
+        let input_cols = self.input.schema().fields().len();
+        let mut column_statistics = Vec::with_capacity(win_cols + input_cols);
+        column_statistics.extend(input_stat.column_statistics);
+        for _ in 0..win_cols {
+            column_statistics.push(ColumnStatistics::new_unknown())
+        }
+        Ok(Statistics {
+            num_rows: input_stat.num_rows,
+            column_statistics,
+            total_byte_size: Precision::Absent,
+        })
     }
 }
 
@@ -192,6 +204,7 @@ mod test {
     use arrow::{array::*, datatypes::*, record_batch::RecordBatch};
     use datafusion::{
         assert_batches_eq,
+        common::stats::Precision,
         physical_expr::{expressions::Column, PhysicalSortExpr},
         physical_plan::{memory::MemoryExec, ExecutionPlan},
         prelude::SessionContext,
@@ -246,30 +259,31 @@ mod test {
             ("b1", &vec![1, 2, 2, 3, 4, 1, 1]),
             ("c1", &vec![0, 0, 0, 0, 0, 0, 0]),
         );
+        let window_exprs = vec![
+            WindowExpr::new(
+                WindowFunction::RankLike(WindowRankType::RowNumber),
+                vec![],
+                Arc::new(Field::new("b1_row_number", DataType::Int32, false)),
+            ),
+            WindowExpr::new(
+                WindowFunction::RankLike(WindowRankType::Rank),
+                vec![],
+                Arc::new(Field::new("b1_rank", DataType::Int32, false)),
+            ),
+            WindowExpr::new(
+                WindowFunction::RankLike(WindowRankType::DenseRank),
+                vec![],
+                Arc::new(Field::new("b1_dense_rank", DataType::Int32, false)),
+            ),
+            WindowExpr::new(
+                WindowFunction::Agg(AggFunction::Sum),
+                vec![Arc::new(Column::new("b1", 1))],
+                Arc::new(Field::new("b1_sum", DataType::Int64, false)),
+            ),
+        ];
         let window = Arc::new(WindowExec::try_new(
             input,
-            vec![
-                WindowExpr::new(
-                    WindowFunction::RankLike(WindowRankType::RowNumber),
-                    vec![],
-                    Arc::new(Field::new("b1_row_number", DataType::Int32, false)),
-                ),
-                WindowExpr::new(
-                    WindowFunction::RankLike(WindowRankType::Rank),
-                    vec![],
-                    Arc::new(Field::new("b1_rank", DataType::Int32, false)),
-                ),
-                WindowExpr::new(
-                    WindowFunction::RankLike(WindowRankType::DenseRank),
-                    vec![],
-                    Arc::new(Field::new("b1_dense_rank", DataType::Int32, false)),
-                ),
-                WindowExpr::new(
-                    WindowFunction::Agg(AggFunction::Sum),
-                    vec![Arc::new(Column::new("b1", 1))],
-                    Arc::new(Field::new("b1_sum", DataType::Int64, false)),
-                ),
-            ],
+            window_exprs,
             vec![Arc::new(Column::new("a1", 0))],
             vec![PhysicalSortExpr {
                 expr: Arc::new(Column::new("b1", 1)),
@@ -278,6 +292,7 @@ mod test {
         )?);
         let stream = window.execute(0, task_ctx.clone())?;
         let batches = datafusion::physical_plan::common::collect(stream).await?;
+        let row_count = window.statistics()?.num_rows;
         let expected = vec![
             "+----+----+----+---------------+---------+---------------+--------+",
             "| a1 | b1 | c1 | b1_row_number | b1_rank | b1_dense_rank | b1_sum |",
@@ -292,37 +307,42 @@ mod test {
             "+----+----+----+---------------+---------+---------------+--------+",
         ];
         assert_batches_eq!(expected, &batches);
+        assert_eq!(
+            row_count,
+            Precision::Exact(window_exprs.clone().len() + input.clone().schema().fields().len())
+        );
 
         // test window without partition by clause
         let input = build_table(
             ("a1", &vec![1, 3, 3, 1, 1, 1, 2]),
             ("b1", &vec![1, 1, 1, 2, 2, 3, 4]),
             ("c1", &vec![0, 0, 0, 0, 0, 0, 0]),
         );
+        let window_exprs = vec![
+            WindowExpr::new(
+                WindowFunction::RankLike(WindowRankType::RowNumber),
+                vec![],
+                Arc::new(Field::new("b1_row_number", DataType::Int32, false)),
+            ),
+            WindowExpr::new(
+                WindowFunction::RankLike(WindowRankType::Rank),
+                vec![],
+                Arc::new(Field::new("b1_rank", DataType::Int32, false)),
+            ),
+            WindowExpr::new(
+                WindowFunction::RankLike(WindowRankType::DenseRank),
+                vec![],
+                Arc::new(Field::new("b1_dense_rank", DataType::Int32, false)),
+            ),
+            WindowExpr::new(
+                WindowFunction::Agg(AggFunction::Sum),
+                vec![Arc::new(Column::new("b1", 1))],
+                Arc::new(Field::new("b1_sum", DataType::Int64, false)),
+            ),
+        ];
         let window = Arc::new(WindowExec::try_new(
             input,
-            vec![
-                WindowExpr::new(
-                    WindowFunction::RankLike(WindowRankType::RowNumber),
-                    vec![],
-                    Arc::new(Field::new("b1_row_number", DataType::Int32, false)),
-                ),
-                WindowExpr::new(
-                    WindowFunction::RankLike(WindowRankType::Rank),
-                    vec![],
-                    Arc::new(Field::new("b1_rank", DataType::Int32, false)),
-                ),
-                WindowExpr::new(
-                    WindowFunction::RankLike(WindowRankType::DenseRank),
-                    vec![],
-                    Arc::new(Field::new("b1_dense_rank", DataType::Int32, false)),
-                ),
-                WindowExpr::new(
-                    WindowFunction::Agg(AggFunction::Sum),
-                    vec![Arc::new(Column::new("b1", 1))],
-                    Arc::new(Field::new("b1_sum", DataType::Int64, false)),
-                ),
-            ],
+            window_exprs,
             vec![],
             vec![PhysicalSortExpr {
                 expr: Arc::new(Column::new("b1", 1)),
@@ -331,6 +351,7 @@ mod test {
         )?);
         let stream = window.execute(0, task_ctx.clone())?;
         let batches = datafusion::physical_plan::common::collect(stream).await?;
+        let row_count = window.statistics()?.num_rows;
         let expected = vec![
             "+----+----+----+---------------+---------+---------------+--------+",
             "| a1 | b1 | c1 | b1_row_number | b1_rank | b1_dense_rank | b1_sum |",
@@ -345,6 +366,10 @@ mod test {
             "+----+----+----+---------------+---------+---------------+--------+",
         ];
         assert_batches_eq!(expected, &batches);
+        assert_eq!(
+            row_count,
+            Precision::Exact(window_exprs.clone().len() + input.clone().schema().fields().len())
+        );
         Ok(())
     }
 }