planner: suppress column number in plan_tree explain (#65148)

ref #63118

Author: terry1purcell

pkg/executor/select.go

@@ -1073,18 +1073,21 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
 	sc.OriginalSQL = s.Text()
 	if explainStmt, ok := s.(*ast.ExplainStmt); ok {
 		sc.InExplainStmt = true
-		sc.ExplainFormat = explainStmt.Format
+		// Normalize to lowercase to avoid repeated conversions in shouldRemoveColumnNumbers and other places
+		sc.ExplainFormat = strings.ToLower(explainStmt.Format)
 		sc.InExplainAnalyzeStmt = explainStmt.Analyze
-		sc.IgnoreExplainIDSuffix = strings.ToLower(explainStmt.Format) == types.ExplainFormatBrief || strings.ToLower(explainStmt.Format) == types.ExplainFormatPlanTree
-		sc.InVerboseExplain = strings.ToLower(explainStmt.Format) == types.ExplainFormatVerbose
+		sc.IgnoreExplainIDSuffix = sc.ExplainFormat == types.ExplainFormatBrief || sc.ExplainFormat == types.ExplainFormatPlanTree
+		sc.InVerboseExplain = sc.ExplainFormat == types.ExplainFormatVerbose
 		s = explainStmt.Stmt
 	} else {
 		sc.ExplainFormat = ""
 	}
 	if explainForStmt, ok := s.(*ast.ExplainForStmt); ok {
 		sc.InExplainStmt = true
 		sc.InExplainAnalyzeStmt = true
-		sc.InVerboseExplain = strings.ToLower(explainForStmt.Format) == types.ExplainFormatVerbose
+		// Normalize to lowercase to avoid repeated conversions in shouldRemoveColumnNumbers and other places
+		sc.ExplainFormat = strings.ToLower(explainForStmt.Format)
+		sc.InVerboseExplain = sc.ExplainFormat == types.ExplainFormatVerbose
 	}
 
 	// TODO: Many same bool variables here.
@@ -1246,7 +1249,7 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
 	}
 
 	sc.SetForcePlanCache(fixcontrol.GetBoolWithDefault(vars.OptimizerFixControl, fixcontrol.Fix49736, false))
-	sc.SetAlwaysWarnSkipCache(sc.InExplainStmt && sc.ExplainFormat == "plan_cache")
+	sc.SetAlwaysWarnSkipCache(sc.InExplainStmt && sc.ExplainFormat == types.ExplainFormatPlanCache)
 	errCount, warnCount := vars.StmtCtx.NumErrorWarnings()
 	vars.SysErrorCount = errCount
 	vars.SysWarningCount = warnCount

pkg/expression/BUILD.bazel

@@ -83,6 +83,7 @@ go_library(
         "//pkg/errno",
         "//pkg/expression/exprctx",
         "//pkg/expression/expropt",
+        "//pkg/expression/sessionexpr",
         "//pkg/extension",
         "//pkg/infoschema/context",
         "//pkg/kv",

pkg/expression/column.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/pingcap/errors"
 	"github.com/pingcap/tidb/pkg/expression/exprctx"
+	"github.com/pingcap/tidb/pkg/expression/sessionexpr"
 	"github.com/pingcap/tidb/pkg/meta/model"
 	"github.com/pingcap/tidb/pkg/parser/ast"
 	"github.com/pingcap/tidb/pkg/parser/charset"
@@ -448,17 +449,45 @@ func (col *Column) VecEvalVectorFloat32(ctx EvalContext, input *chunk.Chunk, res
 
 const columnPrefix = "Column#"
 
+// shouldRemoveColumnNumbers checks if column numbers should be removed based on the explain format.
+// This is used for plan_tree format to show "Column" instead of "Column#<number>".
+// Note: ExplainFormat is normalized to lowercase when set, but we use strings.ToLower as a defensive measure
+// in case the format wasn't normalized in some code path.
+func shouldRemoveColumnNumbers(ctx ParamValues) bool {
+	if evalCtx, ok := ctx.(EvalContext); ok {
+		if sessionCtx, ok := evalCtx.(*sessionexpr.EvalContext); ok {
+			stmtCtx := sessionCtx.Sctx().GetSessionVars().StmtCtx
+			// Only check format if we're actually in an explain statement
+			if !stmtCtx.InExplainStmt {
+				return false
+			}
+			format := stmtCtx.ExplainFormat
+			// Use ToLower defensively in case format wasn't normalized in some code path
+			formatLower := strings.ToLower(strings.TrimSpace(format))
+			if formatLower == types.ExplainFormatPlanTree {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 // StringWithCtx implements Expression interface.
-func (col *Column) StringWithCtx(_ ParamValues, redact string) string {
-	return col.string(redact)
+func (col *Column) StringWithCtx(ctx ParamValues, redact string) string {
+	return col.string(redact, shouldRemoveColumnNumbers(ctx))
+}
+
+// StringWithCtxForExplain implements Expression interface with option to remove column numbers for plan_tree format.
+func (col *Column) StringWithCtxForExplain(_ ParamValues, redact string, removeColumnNumbers bool) string {
+	return col.string(redact, removeColumnNumbers)
 }
 
 // String implements Stringer interface.
 func (col *Column) String() string {
-	return col.string(errors.RedactLogDisable)
+	return col.string(errors.RedactLogDisable, false)
 }
 
-func (col *Column) string(redact string) string {
+func (col *Column) string(redact string, removeColumnNumbers bool) string {
 	if col.IsHidden && col.VirtualExpr != nil {
 		// A hidden column without virtual expression indicates it's a stored type.
 		// a virtual column should be able to be stringified without context.
@@ -468,7 +497,12 @@ func (col *Column) string(redact string) string {
 		return col.OrigName
 	}
 	var builder strings.Builder
-	fmt.Fprintf(&builder, "%s%d", columnPrefix, col.UniqueID)
+	if removeColumnNumbers {
+		// For plan_tree format, return "Column" instead of "Column#<number>"
+		builder.WriteString("Column")
+	} else {
+		fmt.Fprintf(&builder, "%s%d", columnPrefix, col.UniqueID)
+	}
 	return builder.String()
 }
 

pkg/expression/explain.go

@@ -111,7 +111,7 @@ func (col *Column) ColumnExplainInfo(ctx ParamValues, normalized bool) string {
 	if normalized {
 		return col.ColumnExplainInfoNormalized()
 	}
-	return col.StringWithCtx(ctx, errors.RedactLogDisable)
+	return col.StringWithCtxForExplain(ctx, errors.RedactLogDisable, shouldRemoveColumnNumbers(ctx))
 }
 
 // ColumnExplainInfoNormalized returns the normalized explained info for column.
@@ -187,24 +187,37 @@ func (expr *Constant) format(dt types.Datum) string {
 // ExplainExpressionList generates explain information for a list of expressions.
 func ExplainExpressionList(ctx EvalContext, exprs []Expression, schema *Schema, redactMode string) string {
 	builder := &strings.Builder{}
+	// Check explain format once at the start - it doesn't change during a single explain output
+	removeColNums := shouldRemoveColumnNumbers(ctx)
 	for i, expr := range exprs {
 		switch expr := expr.(type) {
 		case *Column, *CorrelatedColumn:
-			builder.WriteString(expr.StringWithCtx(ctx, redactMode))
-			if expr.StringWithCtx(ctx, redactMode) != schema.Columns[i].StringWithCtx(ctx, redactMode) {
+			// Both Column and CorrelatedColumn use the same StringWithCtxForExplain method
+			// (CorrelatedColumn embeds Column), so they can share the same logic
+			var col *Column
+			switch c := expr.(type) {
+			case *Column:
+				col = c
+			case *CorrelatedColumn:
+				col = &c.Column
+			}
+			exprStr := col.StringWithCtxForExplain(ctx, redactMode, removeColNums)
+			schemaColStr := schema.Columns[i].StringWithCtxForExplain(ctx, redactMode, removeColNums)
+			builder.WriteString(exprStr)
+			if exprStr != schemaColStr {
 				// simple col projected again with another uniqueID without origin name.
 				builder.WriteString("->")
-				builder.WriteString(schema.Columns[i].StringWithCtx(ctx, redactMode))
+				builder.WriteString(schemaColStr)
 			}
 		case *Constant:
 			v := expr.StringWithCtx(ctx, errors.RedactLogDisable)
 			redact.WriteRedact(builder, v, redactMode)
 			builder.WriteString("->")
-			builder.WriteString(schema.Columns[i].StringWithCtx(ctx, redactMode))
+			builder.WriteString(schema.Columns[i].StringWithCtxForExplain(ctx, redactMode, removeColNums))
 		default:
 			builder.WriteString(expr.StringWithCtx(ctx, redactMode))
 			builder.WriteString("->")
-			builder.WriteString(schema.Columns[i].StringWithCtx(ctx, redactMode))
+			builder.WriteString(schema.Columns[i].StringWithCtxForExplain(ctx, redactMode, removeColNums))
 		}
 		if i+1 < len(exprs) {
 			builder.WriteString(", ")

pkg/expression/test/constantpropagation/constant_propagation_test.go

@@ -49,8 +49,8 @@ func TestConstantPropagation(t *testing.T) {
   col_36 binary(117) NOT NULL DEFAULT 'k#Vf)%G$9T6)'
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci`)
 	tk.MustQuery(`explain format='plan_tree' select /*+ NO_HASH_JOIN( t373b8b5b , tafab9ab4 */ tafab9ab4.col_32 as r0 , substring_index( tafab9ab4.col_36 , ',' , 2 ) as r1 , tafab9ab4.col_32 as r2 from t373b8b5b join tafab9ab4 on t373b8b5b.col_53 = tafab9ab4.col_35 where tafab9ab4.col_35 in ( 78 ,177 ) and t373b8b5b.col_53 between 0 and 1 order by r0,r1,r2`).Check(testkit.Rows(
-		`Sort root  test.tafab9ab4.col_32, Column#7`,
-		`└─Projection root  test.tafab9ab4.col_32, substring_index(test.tafab9ab4.col_36, ,, 2)->Column#7, test.tafab9ab4.col_32`,
+		`Sort root  test.tafab9ab4.col_32, Column`,
+		`└─Projection root  test.tafab9ab4.col_32, substring_index(test.tafab9ab4.col_36, ,, 2)->Column, test.tafab9ab4.col_32`,
 		`  └─HashJoin root  inner join, equal:[eq(test.t373b8b5b.col_53, test.tafab9ab4.col_35)]`,
 		`    ├─TableReader(Build) root  data:Selection`,
 		`    │ └─Selection cop[tikv]  ge(test.t373b8b5b.col_53, 0), in(test.t373b8b5b.col_53, 78, 177), le(test.t373b8b5b.col_53, 1)`,