feat: refine the rule PushDownFilterWindowTopN in case top n is equal to 0. (#16830)

* top n 0

Signed-off-by: coldWater <forsaken628@gmail.com>

* test

Signed-off-by: coldWater <forsaken628@gmail.com>

* rename

Signed-off-by: coldWater <forsaken628@gmail.com>

* fix

Signed-off-by: coldWater <forsaken628@gmail.com>

---------

Signed-off-by: coldWater <forsaken628@gmail.com>

Author: forsaken628

src/query/sql/src/planner/optimizer/rule/factory.rs

@@ -92,7 +92,9 @@ impl RuleFactory {
             }
             RuleID::PushDownFilterAggregate => Ok(Box::new(RulePushDownFilterAggregate::new())),
             RuleID::PushDownFilterWindow => Ok(Box::new(RulePushDownFilterWindow::new())),
-            RuleID::PushDownFilterWindowRank => Ok(Box::new(RulePushDownFilterWindowTopN::new())),
+            RuleID::PushDownFilterWindowTopN => {
+                Ok(Box::new(RulePushDownFilterWindowTopN::new(ctx.metadata)))
+            }
             RuleID::EliminateFilter => Ok(Box::new(RuleEliminateFilter::new(ctx.metadata))),
             RuleID::MergeEvalScalar => Ok(Box::new(RuleMergeEvalScalar::new())),
             RuleID::MergeFilter => Ok(Box::new(RuleMergeFilter::new())),

src/query/sql/src/planner/optimizer/rule/rewrite/rule_push_down_filter_window_top_n.rs

@@ -16,21 +16,28 @@ use std::sync::Arc;
 
 use databend_common_exception::Result;
 use databend_common_expression::type_check::check_number;
+use databend_common_expression::DataField;
+use databend_common_expression::DataSchemaRefExt;
 use databend_common_expression::FunctionContext;
 use databend_common_functions::BUILTIN_FUNCTIONS;
 
 use crate::optimizer::extract::Matcher;
 use crate::optimizer::rule::Rule;
 use crate::optimizer::rule::TransformResult;
+use crate::optimizer::RelExpr;
 use crate::optimizer::RuleID;
 use crate::optimizer::SExpr;
 use crate::plans::ComparisonOp;
+use crate::plans::ConstantTableScan;
 use crate::plans::Filter;
+use crate::plans::Operator;
 use crate::plans::RelOp;
+use crate::plans::RelOperator;
 use crate::plans::ScalarExpr;
 use crate::plans::Sort;
 use crate::plans::Window;
 use crate::plans::WindowFuncType;
+use crate::MetadataRef;
 
 /// Input:  Filter
 ///           \
@@ -45,13 +52,15 @@ use crate::plans::WindowFuncType;
 ///              Sort(top n)
 pub struct RulePushDownFilterWindowTopN {
     id: RuleID,
+    metadata: MetadataRef,
     matchers: Vec<Matcher>,
 }
 
 impl RulePushDownFilterWindowTopN {
-    pub fn new() -> Self {
+    pub fn new(metadata: MetadataRef) -> Self {
         Self {
-            id: RuleID::PushDownFilterWindowRank,
+            id: RuleID::PushDownFilterWindowTopN,
+            metadata,
             matchers: vec![Matcher::MatchOp {
                 op_type: RelOp::Filter,
                 children: vec![Matcher::MatchOp {
@@ -93,7 +102,22 @@ impl Rule for RulePushDownFilterWindowTopN {
         };
 
         if top_n == 0 {
-            // TODO
+            let output_columns = s_expr
+                .plan()
+                .derive_relational_prop(&RelExpr::with_s_expr(s_expr))?
+                .output_columns
+                .clone();
+            let metadata = self.metadata.read();
+            let mut columns = output_columns.iter().copied().collect::<Vec<_>>();
+            columns.sort();
+            let fields = columns
+                .into_iter()
+                .map(|col| DataField::new(&col.to_string(), metadata.column(col).data_type()))
+                .collect::<Vec<_>>();
+            let empty_scan =
+                ConstantTableScan::new_empty_scan(DataSchemaRefExt::create(fields), output_columns);
+            let result = SExpr::create_leaf(Arc::new(RelOperator::ConstantTableScan(empty_scan)));
+            state.add_result(result);
             return Ok(());
         }
 

src/query/sql/src/planner/optimizer/rule/rule.rs

@@ -37,7 +37,7 @@ pub static DEFAULT_REWRITE_RULES: LazyLock<Vec<RuleID>> = LazyLock::new(|| {
         RuleID::PushDownFilterUnion,
         RuleID::PushDownFilterAggregate,
         RuleID::PushDownFilterWindow,
-        RuleID::PushDownFilterWindowRank,
+        RuleID::PushDownFilterWindowTopN,
         RuleID::PushDownFilterSort,
         RuleID::PushDownFilterEvalScalar,
         RuleID::PushDownFilterJoin,
@@ -91,7 +91,7 @@ pub enum RuleID {
     PushDownFilterSort,
     PushDownFilterProjectSet,
     PushDownFilterWindow,
-    PushDownFilterWindowRank,
+    PushDownFilterWindowTopN,
     PushDownLimit,
     PushDownLimitUnion,
     PushDownLimitOuterJoin,
@@ -142,7 +142,7 @@ impl Display for RuleID {
             RuleID::PushDownSortEvalScalar => write!(f, "PushDownSortEvalScalar"),
             RuleID::PushDownLimitWindow => write!(f, "PushDownLimitWindow"),
             RuleID::PushDownFilterWindow => write!(f, "PushDownFilterWindow"),
-            RuleID::PushDownFilterWindowRank => write!(f, "PushDownFilterWindowRank"),
+            RuleID::PushDownFilterWindowTopN => write!(f, "PushDownFilterWindowTopN"),
             RuleID::EliminateEvalScalar => write!(f, "EliminateEvalScalar"),
             RuleID::EliminateFilter => write!(f, "EliminateFilter"),
             RuleID::EliminateSort => write!(f, "EliminateSort"),

tests/sqllogictests/suites/mode/standalone/explain/window.test

@@ -541,9 +541,17 @@ CompoundBlockOperator(Project) × 1
                 SyncReadParquetDataTransform × 1
                   BlockPartitionSource × 1
 
+# top n 0
+query T
+explain optimized select time, rowkey from (select *, row_number() over(partition by rowkey order by time desc) as rn from table43764_orc) a where rn < 1
+----
+EvalScalar
+├── scalars: [a.rowkey (#0) AS (#0), table43764_orc.rowkey (#0) AS (#0), a.time (#1) AS (#1), table43764_orc.time (#1) AS (#1), table43764_orc.sirc_action (#2) AS (#2), table43764_orc.sirc_operation_count (#3) AS (#3), table43764_orc.akc087 (#4) AS (#4), table43764_orc.aae035 (#5) AS (#5), row_number() OVER ( PARTITION BY rowkey ORDER BY time DESC ) (#6) AS (#6), a.rn (#6) AS (#7)]
+└── EmptyResultScan
+
 # same order multi window
 query T
-explain  pipeline select *,lead(number,1, 42) over (order by number), lead(number,2,44) over (order by number), lead(number,3,44) over (order by number) from numbers(5);
+explain pipeline select *,lead(number,1, 42) over (order by number), lead(number,2,44) over (order by number), lead(number,3,44) over (order by number) from numbers(5);
 ----
 CompoundBlockOperator(Project) × 1
   Transform Window × 1