plan: support ? in Order By / Group By / Limit Offset clauses (pingcap#8206)

Author: dbjoa

executor/prepared.go

@@ -26,7 +26,6 @@ import (
 	plannercore "github.com/pingcap/tidb/planner/core"
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
-	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/types/parser_driver"
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/sqlexec"
@@ -161,7 +160,7 @@ func (e *PrepareExec) Next(ctx context.Context, chk *chunk.Chunk) error {
 
 	// We try to build the real statement of preparedStmt.
 	for i := range prepared.Params {
-		prepared.Params[i].(*driver.ParamMarkerExpr).Datum = types.NewIntDatum(0)
+		prepared.Params[i].(*driver.ParamMarkerExpr).Datum.SetNull()
 	}
 	var p plannercore.Plan
 	p, err = plannercore.BuildLogicalPlan(e.ctx, stmt, e.is)

executor/prepared_test.go

@@ -688,3 +688,60 @@ func (s *testSuite) TestPrepareDealloc(c *C) {
 	tk.MustExec("deallocate prepare stmt4")
 	c.Assert(tk.Se.PreparedPlanCache().Size(), Equals, 0)
 }
+
+func (s *testSuite) TestPreparedIssue8153(c *C) {
+	orgEnable := plannercore.PreparedPlanCacheEnabled()
+	orgCapacity := plannercore.PreparedPlanCacheCapacity
+	orgMemGuardRatio := plannercore.PreparedPlanCacheMemoryGuardRatio
+	orgMaxMemory := plannercore.PreparedPlanCacheMaxMemory
+	defer func() {
+		plannercore.SetPreparedPlanCache(orgEnable)
+		plannercore.PreparedPlanCacheCapacity = orgCapacity
+		plannercore.PreparedPlanCacheMemoryGuardRatio = orgMemGuardRatio
+		plannercore.PreparedPlanCacheMaxMemory = orgMaxMemory
+	}()
+	flags := []bool{false, true}
+	for _, flag := range flags {
+		var err error
+		plannercore.SetPreparedPlanCache(flag)
+		plannercore.PreparedPlanCacheCapacity = 100
+		plannercore.PreparedPlanCacheMemoryGuardRatio = 0.1
+		plannercore.PreparedPlanCacheMaxMemory, err = memory.MemTotal()
+		tk := testkit.NewTestKit(c, s.store)
+		tk.MustExec("use test")
+		tk.MustExec("drop table if exists t")
+		tk.MustExec("create table t (a int, b int)")
+		tk.MustExec("insert into t (a, b) values (1,3), (2,2), (3,1)")
+
+		tk.MustExec(`prepare stmt from 'select * from t order by ? asc'`)
+		r := tk.MustQuery(`execute stmt using @param;`)
+		r.Check(testkit.Rows("1 3", "2 2", "3 1"))
+
+		tk.MustExec(`set @param = 1`)
+		r = tk.MustQuery(`execute stmt using @param;`)
+		r.Check(testkit.Rows("1 3", "2 2", "3 1"))
+
+		tk.MustExec(`set @param = 2`)
+		r = tk.MustQuery(`execute stmt using @param;`)
+		r.Check(testkit.Rows("3 1", "2 2", "1 3"))
+
+		tk.MustExec(`set @param = 3`)
+		_, err = tk.Exec(`execute stmt using @param;`)
+		c.Assert(err.Error(), Equals, "[planner:1054]Unknown column '?' in 'order clause'")
+
+		tk.MustExec(`set @param = '##'`)
+		r = tk.MustQuery(`execute stmt using @param;`)
+		r.Check(testkit.Rows("1 3", "2 2", "3 1"))
+
+		tk.MustExec("insert into t (a, b) values (1,1), (1,2), (2,1), (2,3), (3,2), (3,3)")
+		tk.MustExec(`prepare stmt from 'select ?, sum(a) from t group by ?'`)
+
+		tk.MustExec(`set @a=1,@b=1`)
+		r = tk.MustQuery(`execute stmt using @a,@b;`)
+		r.Check(testkit.Rows("1 18"))
+
+		tk.MustExec(`set @a=1,@b=2`)
+		_, err = tk.Exec(`execute stmt using @a,@b;`)
+		c.Assert(err.Error(), Equals, "[planner:1056]Can't group on 'sum(a)'")
+	}
+}

expression/simple_rewriter.go

@@ -151,7 +151,7 @@ func (sr *simpleRewriter) Leave(originInNode ast.Node) (retNode ast.Node, ok boo
 		}
 	case *driver.ParamMarkerExpr:
 		var value Expression
-		value, sr.err = GetParamExpression(sr.ctx, v, sr.useCache())
+		value, sr.err = GetParamExpression(sr.ctx, v)
 		if sr.err != nil {
 			return retNode, false
 		}

expression/util.go

@@ -511,7 +511,8 @@ func DatumToConstant(d types.Datum, tp byte) *Constant {
 }
 
 // GetParamExpression generate a getparam function expression.
-func GetParamExpression(ctx sessionctx.Context, v *driver.ParamMarkerExpr, useCache bool) (Expression, error) {
+func GetParamExpression(ctx sessionctx.Context, v *driver.ParamMarkerExpr) (Expression, error) {
+	useCache := ctx.GetSessionVars().StmtCtx.UseCache
 	tp := types.NewFieldType(mysql.TypeUnspecified)
 	types.DefaultParamTypeForValue(v.GetValue(), tp)
 	value := &Constant{Value: v.Datum, RetType: tp}
@@ -526,3 +527,51 @@ func GetParamExpression(ctx sessionctx.Context, v *driver.ParamMarkerExpr, useCa
 	}
 	return value, nil
 }
+
+// ConstructPositionExpr constructs PositionExpr with the given ParamMarkerExpr.
+func ConstructPositionExpr(p *driver.ParamMarkerExpr) *ast.PositionExpr {
+	return &ast.PositionExpr{P: p}
+}
+
+// PosFromPositionExpr generates a position value from PositionExpr.
+func PosFromPositionExpr(ctx sessionctx.Context, v *ast.PositionExpr) (int, bool, error) {
+	if v.P == nil {
+		return v.N, false, nil
+	}
+	value, err := GetParamExpression(ctx, v.P.(*driver.ParamMarkerExpr))
+	if err != nil {
+		return 0, true, err
+	}
+	pos, isNull, err := GetIntFromConstant(ctx, value)
+	if err != nil || isNull {
+		return 0, true, errors.Trace(err)
+	}
+	return pos, false, nil
+}
+
+// GetStringFromConstant gets a string value from the Constant expression.
+func GetStringFromConstant(ctx sessionctx.Context, value Expression) (string, bool, error) {
+	con, ok := value.(*Constant)
+	if !ok {
+		err := errors.Errorf("Not a Constant expression %+v", value)
+		return "", true, errors.Trace(err)
+	}
+	str, isNull, err := con.EvalString(ctx, chunk.Row{})
+	if err != nil || isNull {
+		return "", true, errors.Trace(err)
+	}
+	return str, false, nil
+}
+
+// GetIntFromConstant gets an interger value from the Constant expression.
+func GetIntFromConstant(ctx sessionctx.Context, value Expression) (int, bool, error) {
+	str, isNull, err := GetStringFromConstant(ctx, value)
+	if err != nil || isNull {
+		return 0, true, errors.Trace(err)
+	}
+	intNum, err := strconv.Atoi(str)
+	if err != nil {
+		return 0, true, nil
+	}
+	return intNum, false, nil
+}

planner/core/cacheable_checker.go

@@ -55,6 +55,20 @@ func (checker *cacheableChecker) Enter(in ast.Node) (out ast.Node, skipChildren
 			checker.cacheable = false
 			return in, true
 		}
+	case *ast.OrderByClause:
+		for _, item := range node.Items {
+			if _, isParamMarker := item.Expr.(*driver.ParamMarkerExpr); isParamMarker {
+				checker.cacheable = false
+				return in, true
+			}
+		}
+	case *ast.GroupByClause:
+		for _, item := range node.Items {
+			if _, isParamMarker := item.Expr.(*driver.ParamMarkerExpr); isParamMarker {
+				checker.cacheable = false
+				return in, true
+			}
+		}
 	case *ast.Limit:
 		if node.Count != nil {
 			if _, isParamMarker := node.Count.(*driver.ParamMarkerExpr); isParamMarker {

planner/core/cacheable_checker_test.go

@@ -177,4 +177,18 @@ func (s *testCacheableSuite) TestCacheable(c *C) {
 		Limit: limitStmt,
 	}
 	c.Assert(Cacheable(stmt), IsTrue)
+
+	paramExpr := &driver.ParamMarkerExpr{}
+	orderByClause := &ast.OrderByClause{Items: []*ast.ByItem{{Expr: paramExpr}}}
+	stmt = &ast.SelectStmt{
+		OrderBy: orderByClause,
+	}
+	c.Assert(Cacheable(stmt), IsFalse)
+
+	valExpr := &driver.ValueExpr{}
+	orderByClause = &ast.OrderByClause{Items: []*ast.ByItem{{Expr: valExpr}}}
+	stmt = &ast.SelectStmt{
+		OrderBy: orderByClause,
+	}
+	c.Assert(Cacheable(stmt), IsTrue)
 }

planner/core/errors.go

@@ -28,6 +28,7 @@ const (
 
 	codeWrongUsage                   = mysql.ErrWrongUsage
 	codeAmbiguous                    = mysql.ErrNonUniq
+	codeUnknown                      = mysql.ErrUnknown
 	codeUnknownColumn                = mysql.ErrBadField
 	codeUnknownTable                 = mysql.ErrUnknownTable
 	codeWrongArguments               = mysql.ErrWrongArguments
@@ -64,6 +65,7 @@ var (
 
 	ErrWrongUsage                   = terror.ClassOptimizer.New(codeWrongUsage, mysql.MySQLErrName[mysql.ErrWrongUsage])
 	ErrAmbiguous                    = terror.ClassOptimizer.New(codeAmbiguous, mysql.MySQLErrName[mysql.ErrNonUniq])
+	ErrUnknown                      = terror.ClassOptimizer.New(codeUnknown, mysql.MySQLErrName[mysql.ErrUnknown])
 	ErrUnknownColumn                = terror.ClassOptimizer.New(codeUnknownColumn, mysql.MySQLErrName[mysql.ErrBadField])
 	ErrUnknownTable                 = terror.ClassOptimizer.New(codeUnknownTable, mysql.MySQLErrName[mysql.ErrUnknownTable])
 	ErrWrongArguments               = terror.ClassOptimizer.New(codeWrongArguments, mysql.MySQLErrName[mysql.ErrWrongArguments])

planner/core/expression_rewriter.go

@@ -756,7 +756,7 @@ func (er *expressionRewriter) Leave(originInNode ast.Node) (retNode ast.Node, ok
 		er.ctxStack = append(er.ctxStack, value)
 	case *driver.ParamMarkerExpr:
 		var value expression.Expression
-		value, er.err = expression.GetParamExpression(er.ctx, v, er.useCache())
+		value, er.err = expression.GetParamExpression(er.ctx, v)
 		if er.err != nil {
 			return retNode, false
 		}
@@ -941,10 +941,26 @@ func (er *expressionRewriter) isNullToExpression(v *ast.IsNullExpr) {
 }
 
 func (er *expressionRewriter) positionToScalarFunc(v *ast.PositionExpr) {
-	if v.N > 0 && v.N <= er.schema.Len() {
-		er.ctxStack = append(er.ctxStack, er.schema.Columns[v.N-1])
+	pos := v.N
+	str := strconv.Itoa(pos)
+	if v.P != nil {
+		stkLen := len(er.ctxStack)
+		val := er.ctxStack[stkLen-1]
+		intNum, isNull, err := expression.GetIntFromConstant(er.ctx, val)
+		str = "?"
+		if err == nil {
+			if isNull {
+				return
+			}
+			pos = intNum
+			er.ctxStack = er.ctxStack[:stkLen-1]
+		}
+		er.err = err
+	}
+	if er.err == nil && pos > 0 && pos <= er.schema.Len() {
+		er.ctxStack = append(er.ctxStack, er.schema.Columns[pos-1])
 	} else {
-		er.err = ErrUnknownColumn.GenWithStackByArgs(strconv.Itoa(v.N), clauseMsg[er.b.curClause])
+		er.err = ErrUnknownColumn.GenWithStackByArgs(str, clauseMsg[er.b.curClause])
 	}
 }