plan: use Column.UniqueID in conditionChecker of ranger (#8236)

planner/core/rule_partition_processor.go

@@ -135,7 +135,7 @@ func (s *partitionProcessor) canBePrune(ctx sessionctx.Context, col *expression.
 	conds = expression.PropagateConstant(ctx, conds)
 
 	// Calculate the column range to prune.
-	accessConds := ranger.ExtractAccessConditionsForColumn(conds, col.ColName)
+	accessConds := ranger.ExtractAccessConditionsForColumn(conds, col.UniqueID)
 	r, err := ranger.BuildColumnRange(accessConds, ctx.GetSessionVars().StmtCtx, col.RetType)
 	if err != nil {
 		return false, errors.Trace(err)

statistics/selectivity.go

@@ -244,7 +244,7 @@ func getMaskAndRanges(ctx sessionctx.Context, exprs []expression.Expression, ran
 	var accessConds, remainedConds []expression.Expression
 	switch rangeType {
 	case ranger.ColumnRangeType:
-		accessConds = ranger.ExtractAccessConditionsForColumn(exprs, cols[0].ColName)
+		accessConds = ranger.ExtractAccessConditionsForColumn(exprs, cols[0].UniqueID)
 		ranges, err = ranger.BuildColumnRange(accessConds, sc, cols[0].RetType)
 	case ranger.IndexRangeType:
 		var res *ranger.DetachRangeResult

table/tables/partition.go

@@ -115,20 +115,23 @@ func generatePartitionExpr(tblInfo *model.TableInfo) (*PartitionExpr, error) {
 	partitionPruneExprs := make([]expression.Expression, 0, len(pi.Definitions))
 	locateExprs := make([]expression.Expression, 0, len(pi.Definitions))
 	var buf bytes.Buffer
+	dbName := model.NewCIStr(ctx.GetSessionVars().CurrentDB)
+	columns := expression.ColumnInfos2ColumnsWithDBName(ctx, dbName, tblInfo.Name, tblInfo.Columns)
+	schema := expression.NewSchema(columns...)
 	for i := 0; i < len(pi.Definitions); i++ {
 		if strings.EqualFold(pi.Definitions[i].LessThan[0], "MAXVALUE") {
 			// Expr less than maxvalue is always true.
 			fmt.Fprintf(&buf, "true")
 		} else {
 			fmt.Fprintf(&buf, "((%s) < (%s))", pi.Expr, pi.Definitions[i].LessThan[0])
 		}
-		expr, err := expression.ParseSimpleExprWithTableInfo(ctx, buf.String(), tblInfo)
+		exprs, err := expression.ParseSimpleExprsWithSchema(ctx, buf.String(), schema)
 		if err != nil {
 			// If it got an error here, ddl may hang forever, so this error log is important.
 			log.Error("wrong table partition expression:", errors.ErrorStack(err), buf.String())
 			return nil, errors.Trace(err)
 		}
-		locateExprs = append(locateExprs, expr)
+		locateExprs = append(locateExprs, exprs[0])
 
 		if i > 0 {
 			fmt.Fprintf(&buf, " and ((%s) >= (%s))", pi.Expr, pi.Definitions[i-1].LessThan[0])
@@ -137,8 +140,8 @@ func generatePartitionExpr(tblInfo *model.TableInfo) (*PartitionExpr, error) {
 			fmt.Fprintf(&buf, " or ((%s) is null)", pi.Expr)
 
 			// Extracts the column of the partition expression, it will be used by partition prunning.
-			if tmp, err1 := expression.ParseSimpleExprWithTableInfo(ctx, pi.Expr, tblInfo); err1 == nil {
-				if col, ok := tmp.(*expression.Column); ok {
+			if tmps, err1 := expression.ParseSimpleExprsWithSchema(ctx, pi.Expr, schema); err1 == nil {
+				if col, ok := tmps[0].(*expression.Column); ok {
 					column = col
 				}
 			}
@@ -147,13 +150,13 @@ func generatePartitionExpr(tblInfo *model.TableInfo) (*PartitionExpr, error) {
 			}
 		}
 
-		expr, err = expression.ParseSimpleExprWithTableInfo(ctx, buf.String(), tblInfo)
+		exprs, err = expression.ParseSimpleExprsWithSchema(ctx, buf.String(), schema)
 		if err != nil {
 			// If it got an error here, ddl may hang forever, so this error log is important.
 			log.Error("wrong table partition expression:", errors.ErrorStack(err), buf.String())
 			return nil, errors.Trace(err)
 		}
-		partitionPruneExprs = append(partitionPruneExprs, expr)
+		partitionPruneExprs = append(partitionPruneExprs, exprs[0])
 		buf.Reset()
 	}
 	return &PartitionExpr{

util/ranger/checker.go

@@ -15,14 +15,13 @@ package ranger
 
 import (
 	"github.com/pingcap/parser/ast"
-	"github.com/pingcap/parser/model"
 	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/types"
 )
 
 // conditionChecker checks if this condition can be pushed to index planner.
 type conditionChecker struct {
-	colName       model.CIStr
+	colUniqueID   int64
 	shouldReserve bool // check if a access condition should be reserved in filter conditions.
 	length        int
 }
@@ -135,8 +134,5 @@ func (c *conditionChecker) checkColumn(expr expression.Expression) bool {
 	if !ok {
 		return false
 	}
-	if c.colName.L != "" {
-		return c.colName.L == col.ColName.L
-	}
-	return true
+	return c.colUniqueID == col.UniqueID
 }

util/ranger/detacher.go

@@ -16,7 +16,6 @@ package ranger
 import (
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser/ast"
-	"github.com/pingcap/parser/model"
 	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/types"
@@ -174,7 +173,7 @@ func detachCNFCondAndBuildRangeForIndex(sctx sessionctx.Context, conditions []ex
 		return res, nil
 	}
 	checker := &conditionChecker{
-		colName:       cols[eqOrInCount].ColName,
+		colUniqueID:   cols[eqOrInCount].UniqueID,
 		length:        lengths[eqOrInCount],
 		shouldReserve: lengths[eqOrInCount] != types.UnspecifiedLength,
 	}
@@ -257,7 +256,7 @@ func detachDNFCondAndBuildRangeForIndex(sctx sessionctx.Context, condition *expr
 	cols []*expression.Column, newTpSlice []*types.FieldType, lengths []int) ([]*Range, []expression.Expression, bool, error) {
 	sc := sctx.GetSessionVars().StmtCtx
 	firstColumnChecker := &conditionChecker{
-		colName:       cols[0].ColName,
+		colUniqueID:   cols[0].UniqueID,
 		shouldReserve: lengths[0] != types.UnspecifiedLength,
 		length:        lengths[0],
 	}
@@ -376,13 +375,10 @@ func removeAccessConditions(conditions, accessConds []expression.Expression) []e
 }
 
 // ExtractAccessConditionsForColumn detaches the access conditions used for range calculation.
-func ExtractAccessConditionsForColumn(conds []expression.Expression, colName model.CIStr) []expression.Expression {
-	if colName.L == "" {
-		return nil
-	}
+func ExtractAccessConditionsForColumn(conds []expression.Expression, uniqueID int64) []expression.Expression {
 	checker := conditionChecker{
-		colName: colName,
-		length:  types.UnspecifiedLength,
+		colUniqueID: uniqueID,
+		length:      types.UnspecifiedLength,
 	}
 	accessConds := make([]expression.Expression, 0, 8)
 	return expression.Filter(accessConds, conds, checker.check)
@@ -392,8 +388,8 @@ func ExtractAccessConditionsForColumn(conds []expression.Expression, colName mod
 // calculating the table range.
 func DetachCondsForTableRange(sctx sessionctx.Context, conds []expression.Expression, col *expression.Column) (accessContditions, otherConditions []expression.Expression) {
 	checker := &conditionChecker{
-		colName: col.ColName,
-		length:  types.UnspecifiedLength,
+		colUniqueID: col.UniqueID,
+		length:      types.UnspecifiedLength,
 	}
 	return detachColumnCNFConditions(sctx, conds, checker)
 }

util/ranger/ranger_test.go

@@ -954,11 +954,40 @@ func (s *testRangerSuite) TestColumnRange(c *C) {
 		}
 		col := expression.ColInfo2Col(sel.Schema().Columns, ds.TableInfo().Columns[tt.colPos])
 		c.Assert(col, NotNil)
-		conds = ranger.ExtractAccessConditionsForColumn(conds, col.ColName)
+		conds = ranger.ExtractAccessConditionsForColumn(conds, col.UniqueID)
 		c.Assert(fmt.Sprintf("%s", conds), Equals, tt.accessConds, Commentf("wrong access conditions for expr: %s", tt.exprStr))
 		result, err := ranger.BuildColumnRange(conds, new(stmtctx.StatementContext), col.RetType)
 		c.Assert(err, IsNil)
 		got := fmt.Sprintf("%v", result)
 		c.Assert(got, Equals, tt.resultStr, Commentf("different for expr %s, col: %v", tt.exprStr, col))
 	}
 }
+
+func (s *testRangerSuite) TestIndexRangeElimininatedProjection(c *C) {
+	defer testleak.AfterTest(c)()
+	dom, store, err := newDomainStoreWithBootstrap(c)
+	defer func() {
+		dom.Close()
+		store.Close()
+	}()
+	c.Assert(err, IsNil)
+	testKit := testkit.NewTestKit(c, store)
+	testKit.MustExec("use test")
+	testKit.MustExec("drop table if exists t")
+	testKit.MustExec("create table t(a int not null, b int not null, primary key(a,b))")
+	testKit.MustExec("insert into t values(1,2)")
+	testKit.MustExec("analyze table t")
+	testKit.MustQuery("explain select * from (select * from t union all select ifnull(a,b), b from t) sub where a > 0").Check(testkit.Rows(
+		"Union_11 1.80 root ",
+		"├─IndexReader_14 1.00 root index:IndexScan_13",
+		"│ └─IndexScan_13 1.00 cop table:t, index:a, b, range:(0 +inf,+inf +inf], keep order:false",
+		"└─Projection_16 0.80 root ifnull(test.t.a, test.t.b), test.t.b",
+		"  └─TableReader_19 0.80 root data:Selection_18",
+		"    └─Selection_18 0.80 cop gt(ifnull(test.t.a, test.t.b), 0)",
+		"      └─TableScan_17 1.00 cop table:t, range:[-inf,+inf], keep order:false",
+	))
+	testKit.MustQuery("select * from (select * from t union all select ifnull(a,b), b from t) sub where a > 0").Check(testkit.Rows(
+		"1 2",
+		"1 2",
+	))
+}