planner: support window function (#8630)

expression/aggregation/window_func.go

@@ -0,0 +1,29 @@
+// Copyright 2018 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package aggregation
+
+import (
+	"github.com/pingcap/tidb/expression"
+	"github.com/pingcap/tidb/sessionctx"
+)
+
+// WindowFuncDesc describes a window function signature, only used in planner.
+type WindowFuncDesc struct {
+	baseFuncDesc
+}
+
+// NewWindowFuncDesc creates a window function signature descriptor.
+func NewWindowFuncDesc(ctx sessionctx.Context, name string, args []expression.Expression) *WindowFuncDesc {
+	return &WindowFuncDesc{newBaseFuncDesc(ctx, name, args)}
+}

go.mod

@@ -48,7 +48,7 @@ require (
 	github.com/pingcap/gofail v0.0.0-20181217135706-6a951c1e42c3
 	github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e
 	github.com/pingcap/kvproto v0.0.0-20181203065228-c14302da291c
-	github.com/pingcap/parser v0.0.0-20181225032741-ff56f7f11ed6
+	github.com/pingcap/parser v0.0.0-20190103075927-c065c7404641
 	github.com/pingcap/pd v2.1.0-rc.4+incompatible
 	github.com/pingcap/tidb-tools v2.1.1-0.20181218072513-b2235d442b06+incompatible
 	github.com/pingcap/tipb v0.0.0-20181012112600-11e33c750323

go.sum

@@ -110,8 +110,8 @@ github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e h1:P73/4dPCL96rG
 github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e/go.mod h1:O17XtbryoCJhkKGbT62+L2OlrniwqiGLSqrmdHCMzZw=
 github.com/pingcap/kvproto v0.0.0-20181203065228-c14302da291c h1:Qf5St5XGwKgKQLar9lEXoeO0hJMVaFBj3JqvFguWtVg=
 github.com/pingcap/kvproto v0.0.0-20181203065228-c14302da291c/go.mod h1:Ja9XPjot9q4/3JyCZodnWDGNXt4pKemhIYCvVJM7P24=
-github.com/pingcap/parser v0.0.0-20181225032741-ff56f7f11ed6 h1:ooapyJxH6uSHNvpYjPOggHtd2dzLKwSvYLVzs3OjoM0=
-github.com/pingcap/parser v0.0.0-20181225032741-ff56f7f11ed6/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
+github.com/pingcap/parser v0.0.0-20190103075927-c065c7404641 h1:KTGU8kr2wY+FRiHHs8I5lp385b+OzYnbOr3/tPVw7mU=
+github.com/pingcap/parser v0.0.0-20190103075927-c065c7404641/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
 github.com/pingcap/pd v2.1.0-rc.4+incompatible h1:/buwGk04aHO5odk/+O8ZOXGs4qkUjYTJ2UpCJXna8NE=
 github.com/pingcap/pd v2.1.0-rc.4+incompatible/go.mod h1:nD3+EoYes4+aNNODO99ES59V83MZSI+dFbhyr667a0E=
 github.com/pingcap/tidb-tools v2.1.1-0.20181218072513-b2235d442b06+incompatible h1:Bsd+NHosPVowEGB3BCx+2d8wUQGDTXSSC5ljeNS6cXo=

planner/core/errors.go

@@ -51,6 +51,9 @@ const (
 	codeWrongNumberOfColumnsInSelect = mysql.ErrWrongNumberOfColumnsInSelect
 	codeWrongValueCountOnRow         = mysql.ErrWrongValueCountOnRow
 	codeTablenameNotAllowedHere      = mysql.ErrTablenameNotAllowedHere
+
+	codeWindowInvalidWindowFuncUse      = mysql.ErrWindowInvalidWindowFuncUse
+	codeWindowInvalidWindowFuncAliasUse = mysql.ErrWindowInvalidWindowFuncAliasUse
 )
 
 // error definitions.
@@ -88,6 +91,9 @@ var (
 	ErrNonUniqTable                 = terror.ClassOptimizer.New(codeNonUniqTable, mysql.MySQLErrName[mysql.ErrNonuniqTable])
 	ErrWrongValueCountOnRow         = terror.ClassOptimizer.New(mysql.ErrWrongValueCountOnRow, mysql.MySQLErrName[mysql.ErrWrongValueCountOnRow])
 	ErrViewInvalid                  = terror.ClassOptimizer.New(mysql.ErrViewInvalid, mysql.MySQLErrName[mysql.ErrViewInvalid])
+
+	ErrWindowInvalidWindowFuncUse      = terror.ClassOptimizer.New(codeWindowInvalidWindowFuncUse, mysql.MySQLErrName[mysql.ErrWindowInvalidWindowFuncUse])
+	ErrWindowInvalidWindowFuncAliasUse = terror.ClassOptimizer.New(codeWindowInvalidWindowFuncAliasUse, mysql.MySQLErrName[mysql.ErrWindowInvalidWindowFuncAliasUse])
 )
 
 func init() {
@@ -115,6 +121,9 @@ func init() {
 		codeNonUniqTable:                 mysql.ErrNonuniqTable,
 		codeWrongNumberOfColumnsInSelect: mysql.ErrWrongNumberOfColumnsInSelect,
 		codeWrongValueCountOnRow:         mysql.ErrWrongValueCountOnRow,
+
+		codeWindowInvalidWindowFuncUse:      mysql.ErrWindowInvalidWindowFuncUse,
+		codeWindowInvalidWindowFuncAliasUse: mysql.ErrWindowInvalidWindowFuncAliasUse,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassOptimizer] = mysqlErrCodeMap
 }

planner/core/exhaust_physical_plans.go

@@ -789,6 +789,18 @@ func (la *LogicalApply) exhaustPhysicalPlans(prop *property.PhysicalProperty) []
 	return []PhysicalPlan{apply}
 }
 
+func (p *LogicalWindow) exhaustPhysicalPlans(prop *property.PhysicalProperty) []PhysicalPlan {
+	childProperty := &property.PhysicalProperty{ExpectedCnt: math.MaxFloat64, Items: p.ByItems, Enforced: true}
+	if !prop.IsPrefix(childProperty) {
+		return nil
+	}
+	window := PhysicalWindow{
+		WindowFuncDesc: p.WindowFuncDesc,
+	}.Init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), childProperty)
+	window.SetSchema(p.Schema())
+	return []PhysicalPlan{window}
+}
+
 // exhaustPhysicalPlans is only for implementing interface. DataSource and Dual generate task in `findBestTask` directly.
 func (p *baseLogicalPlan) exhaustPhysicalPlans(_ *property.PhysicalProperty) []PhysicalPlan {
 	panic("baseLogicalPlan.exhaustPhysicalPlans() should never be called.")

planner/core/explain.go

@@ -297,3 +297,9 @@ func (p *PhysicalTopN) ExplainInfo() string {
 	fmt.Fprintf(buffer, ", offset:%v, count:%v", p.Offset, p.Count)
 	return buffer.String()
 }
+
+// ExplainInfo implements PhysicalPlan interface.
+func (p *PhysicalWindow) ExplainInfo() string {
+	// TODO: Add explain info for partition by, order by and frame.
+	return p.WindowFuncDesc.String()
+}

planner/core/expression_rewriter.go

@@ -305,12 +305,25 @@ func (er *expressionRewriter) Enter(inNode ast.Node) (ast.Node, bool) {
 		}
 		er.ctxStack = append(er.ctxStack, expression.NewValuesFunc(er.ctx, col.Index, col.RetType))
 		return inNode, true
+	case *ast.WindowFuncExpr:
+		return er.handleWindowFunction(v)
 	default:
 		er.asScalar = true
 	}
 	return inNode, false
 }
 
+func (er *expressionRewriter) handleWindowFunction(v *ast.WindowFuncExpr) (ast.Node, bool) {
+	windowPlan, err := er.b.buildWindowFunction(er.p, v, er.aggrMap)
+	if err != nil {
+		er.err = err
+		return v, false
+	}
+	er.ctxStack = append(er.ctxStack, windowPlan.GetWindowResultColumn())
+	er.p = windowPlan
+	return v, true
+}
+
 func (er *expressionRewriter) handleCompareSubquery(v *ast.CompareSubqueryExpr) (ast.Node, bool) {
 	v.L.Accept(er)
 	if er.err != nil {
@@ -753,7 +766,7 @@ func (er *expressionRewriter) Leave(originInNode ast.Node) (retNode ast.Node, ok
 	}
 	switch v := inNode.(type) {
 	case *ast.AggregateFuncExpr, *ast.ColumnNameExpr, *ast.ParenthesesExpr, *ast.WhenClause,
-		*ast.SubqueryExpr, *ast.ExistsSubqueryExpr, *ast.CompareSubqueryExpr, *ast.ValuesExpr:
+		*ast.SubqueryExpr, *ast.ExistsSubqueryExpr, *ast.CompareSubqueryExpr, *ast.ValuesExpr, *ast.WindowFuncExpr:
 	case *driver.ValueExpr:
 		value := &expression.Constant{Value: v.Datum, RetType: &v.Type}
 		er.ctxStack = append(er.ctxStack, value)

planner/core/initialize.go

@@ -81,6 +81,8 @@ const (
 	TypeTableReader = "TableReader"
 	// TypeIndexReader is the type of IndexReader.
 	TypeIndexReader = "IndexReader"
+	// TypeWindow is the type of Window.
+	TypeWindow = "Window"
 )
 
 // Init initializes LogicalAggregation.
@@ -231,6 +233,20 @@ func (p PhysicalMaxOneRow) Init(ctx sessionctx.Context, stats *property.StatsInf
 	return &p
 }
 
+// Init initializes LogicalWindow.
+func (p LogicalWindow) Init(ctx sessionctx.Context) *LogicalWindow {
+	p.baseLogicalPlan = newBaseLogicalPlan(ctx, TypeWindow, &p)
+	return &p
+}
+
+// Init initializes PhysicalWindow.
+func (p PhysicalWindow) Init(ctx sessionctx.Context, stats *property.StatsInfo, props ...*property.PhysicalProperty) *PhysicalWindow {
+	p.basePhysicalPlan = newBasePhysicalPlan(ctx, TypeWindow, &p)
+	p.childrenReqProps = props
+	p.stats = stats
+	return &p
+}
+
 // Init initializes Update.
 func (p Update) Init(ctx sessionctx.Context) *Update {
 	p.basePlan = newBasePlan(ctx, TypeUpdate)