planner/core: refine explain for window function

cmd/explaintest/main.go

@@ -87,6 +87,7 @@ func newTester(name string) *tester {
 	t.name = name
 	t.enableQueryLog = true
 	t.ctx = mock.NewContext()
+	t.ctx.GetSessionVars().EnableWindowFunction = true
 
 	return t
 }

cmd/explaintest/r/window_function.result

@@ -0,0 +1,51 @@
+use test;
+drop table if exists t;
+create table t (a int, b int, c timestamp, index idx(a));
+set @@tidb_enable_window_function = 1;
+explain select sum(a) over() from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over()
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over()
+  └─TableReader_10	10000.00	root	data:TableScan_9
+    └─TableScan_9	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo
+explain select sum(a) over(partition by a) from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over(partition by a)
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over(partition by test.t.a)
+  └─IndexReader_11	10000.00	root	index:IndexScan_10
+    └─IndexScan_10	10000.00	cop	table:t, index:a, range:[NULL,+inf], keep order:true, stats:pseudo
+explain select sum(a) over(partition by a order by b) from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over(partition by a order by b)
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over(partition by test.t.a order by test.t.b asc)
+  └─Sort_14	10000.00	root	test.t.a:asc, test.t.b:asc
+    └─TableReader_13	10000.00	root	data:TableScan_12
+      └─TableScan_12	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo
+explain select sum(a) over(partition by a order by b rows unbounded preceding) from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over(partition by a order by b rows unbounded preceding)
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over(partition by test.t.a order by test.t.b asc rows between unbounded preceding and current row)
+  └─Sort_14	10000.00	root	test.t.a:asc, test.t.b:asc
+    └─TableReader_13	10000.00	root	data:TableScan_12
+      └─TableScan_12	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo
+explain select sum(a) over(partition by a order by b rows between 1 preceding and 1 following) from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over(partition by a order by b rows between 1 preceding and 1 following)
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over(partition by test.t.a order by test.t.b asc rows between 1 preceding and 1 following)
+  └─Sort_14	10000.00	root	test.t.a:asc, test.t.b:asc
+    └─TableReader_13	10000.00	root	data:TableScan_12
+      └─TableScan_12	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo
+explain select sum(a) over(partition by a order by b range between 1 preceding and 1 following) from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over(partition by a order by b range between 1 preceding and 1 following)
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over(partition by test.t.a order by test.t.b asc range between 1 preceding and 1 following)
+  └─Sort_14	10000.00	root	test.t.a:asc, test.t.b:asc
+    └─TableReader_13	10000.00	root	data:TableScan_12
+      └─TableScan_12	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo
+explain select sum(a) over(partition by a order by c range between interval '2:30' minute_second preceding and interval '2:30' minute_second following) from t;
+id	count	task	operator info
+Projection_7	10000.00	root	sum(a) over(partition by a order by c range between interval '2:30' minute_second preceding and interval '2:30' minute_second following)
+└─Window_8	10000.00	root	sum(cast(test.t.a)) over(partition by test.t.a order by test.t.c asc range between interval "2:30" "MINUTE_SECOND" preceding and interval "2:30" "MINUTE_SECOND" following)
+  └─Sort_14	10000.00	root	test.t.a:asc, test.t.c:asc
+    └─TableReader_13	10000.00	root	data:TableScan_12
+      └─TableScan_12	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo

cmd/explaintest/t/window_function.test

@@ -0,0 +1,11 @@
+use test;
+drop table if exists t;
+create table t (a int, b int, c timestamp, index idx(a));
+set @@tidb_enable_window_function = 1;
+explain select sum(a) over() from t;
+explain select sum(a) over(partition by a) from t;
+explain select sum(a) over(partition by a order by b) from t;
+explain select sum(a) over(partition by a order by b rows unbounded preceding) from t;
+explain select sum(a) over(partition by a order by b rows between 1 preceding and 1 following) from t;
+explain select sum(a) over(partition by a order by b range between 1 preceding and 1 following) from t;
+explain select sum(a) over(partition by a order by c range between interval '2:30' minute_second preceding and interval '2:30' minute_second following) from t;

planner/core/exhaust_physical_plans.go

@@ -783,6 +783,7 @@ func (p *LogicalWindow) exhaustPhysicalPlans(prop *property.PhysicalProperty) []
 		WindowFuncDesc: p.WindowFuncDesc,
 		PartitionBy:    p.PartitionBy,
 		OrderBy:        p.OrderBy,
+		Frame:          p.Frame,
 	}.Init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), childProperty)
 	window.SetSchema(p.Schema())
 	return []PhysicalPlan{window}

planner/core/explain.go

@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"fmt"
 
+	"github.com/pingcap/parser/ast"
 	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/expression/aggregation"
 )
@@ -298,8 +299,73 @@ func (p *PhysicalTopN) ExplainInfo() string {
 	return buffer.String()
 }
 
+func (p *PhysicalWindow) formatFrameBound(buffer *bytes.Buffer, bound *FrameBound) {
+	if bound.Type == ast.CurrentRow {
+		buffer.WriteString("current row")
+		return
+	}
+	if bound.UnBounded {
+		buffer.WriteString("unbounded")
+	} else if bound.DateCalcFunc != nil {
+		sf := bound.DateCalcFunc.(*expression.ScalarFunction)
+		// for `interval '2:30' minute_second`.
+		fmt.Fprintf(buffer, "interval %s %s", sf.GetArgs()[1].ExplainInfo(), sf.GetArgs()[2].ExplainInfo())
+	} else {
+		fmt.Fprintf(buffer, "%d", bound.Num)
+	}
+	if bound.Type == ast.Preceding {
+		buffer.WriteString(" preceding")
+	} else {
+		buffer.WriteString(" following")
+	}
+}
+
 // ExplainInfo implements PhysicalPlan interface.
 func (p *PhysicalWindow) ExplainInfo() string {
-	// TODO: Add explain info for partition by, order by and frame.
-	return p.WindowFuncDesc.String()
+	buffer := bytes.NewBufferString(p.WindowFuncDesc.String())
+	buffer.WriteString(" over(")
+	isFirst := true
+	if len(p.PartitionBy) > 0 {
+		buffer.WriteString("partition by ")
+		for i, item := range p.PartitionBy {
+			fmt.Fprintf(buffer, "%s", item.Col.ExplainInfo())
+			if i+1 < len(p.PartitionBy) {
+				buffer.WriteString(", ")
+			}
+		}
+		isFirst = false
+	}
+	if len(p.OrderBy) > 0 {
+		if !isFirst {
+			buffer.WriteString(" ")
+		}
+		buffer.WriteString("order by ")
+		for i, item := range p.OrderBy {
+			order := "asc"
+			if item.Desc {
+				order = "desc"
+			}
+			fmt.Fprintf(buffer, "%s %s", item.Col.ExplainInfo(), order)
+			if i+1 < len(p.OrderBy) {
+				buffer.WriteString(", ")
+			}
+		}
+		isFirst = false
+	}
+	if p.Frame != nil {
+		if !isFirst {
+			buffer.WriteString(" ")
+		}
+		if p.Frame.Type == ast.Rows {
+			buffer.WriteString("rows")
+		} else {
+			buffer.WriteString("range")
+		}
+		buffer.WriteString(" between ")
+		p.formatFrameBound(buffer, p.Frame.Start)
+		buffer.WriteString(" and ")
+		p.formatFrameBound(buffer, p.Frame.End)
+	}
+	buffer.WriteString(")")
+	return buffer.String()
 }

planner/core/physical_plans.go

@@ -383,4 +383,5 @@ type PhysicalWindow struct {
 	WindowFuncDesc *aggregation.WindowFuncDesc
 	PartitionBy    []property.Item
 	OrderBy        []property.Item
+	Frame          *WindowFrame
 }