planner: don't recompute the hashcode when generated column substitut…

…ion doesn't happen (#46450) (#46628)

close #42788

planner/core/logical_plan_test.go

@@ -45,6 +45,26 @@ type plannerSuite struct {
  ctx sessionctx.Context
 }
 
+func (p *plannerSuite) GetParser() *parser.Parser {
+ return p.p
+}
+
+func (p *plannerSuite) GetIS() infoschema.InfoSchema {
+ return p.is
+}
+
+func (p *plannerSuite) GetCtx() sessionctx.Context {
+ return p.ctx
+}
+
+func CreatePlannerSuite(sctx sessionctx.Context, is infoschema.InfoSchema) (s *plannerSuite) {
+ s = new(plannerSuite)
+ s.is = is
+ s.p = parser.New()
+ s.ctx = sctx
+ return s
+}
+
 func createPlannerSuite() (s *plannerSuite) {
  s = new(plannerSuite)
  tblInfos := []*model.TableInfo{

planner/core/rule_generate_column_substitute.go

@@ -74,32 +74,47 @@ func collectGenerateColumn(lp LogicalPlan, exprToColumn ExprColumnMap) {
  }
 }
 
-func tryToSubstituteExpr(expr *expression.Expression, sctx sessionctx.Context, candidateExpr expression.Expression, tp types.EvalType, schema *expression.Schema, col *expression.Column) {
- if (*expr).Equal(sctx, candidateExpr) && candidateExpr.GetType().EvalType() == tp &&
+func tryToSubstituteExpr(expr *expression.Expression, sessionCtx sessionctx.Context, candidateExpr expression.Expression, tp types.EvalType, schema *expression.Schema, col *expression.Column) bool {
+ changed := false
+ if (*expr).Equal(sessionCtx, candidateExpr) && candidateExpr.GetType().EvalType() == tp &&
  schema.ColumnIndex(col) != -1 {
  *expr = col
+ changed = true
  }
+ return changed
 }
 
-func substituteExpression(cond expression.Expression, sctx *stmtctx.StatementContext, sessionCtx sessionctx.Context, exprToColumn ExprColumnMap, schema *expression.Schema) {
+// SubstituteExpression is Exported for bench
+func SubstituteExpression(cond expression.Expression, sctx *stmtctx.StatementContext, sessionCtx sessionctx.Context, exprToColumn ExprColumnMap, schema *expression.Schema) bool {
+ return substituteExpression(cond, sctx, sessionCtx, exprToColumn, schema)
+}
+
+func substituteExpression(cond expression.Expression, sctx *stmtctx.StatementContext, sessionCtx sessionctx.Context, exprToColumn ExprColumnMap, schema *expression.Schema) bool {
  sf, ok := cond.(*expression.ScalarFunction)
  if !ok {
- return
+ return false
+ }
+ changed := false
+ collectChanged := func(partial bool) {
+ if partial && !changed {
+ changed = true
+ }
  }
  defer func() {
  // If the argument is not changed, hash code doesn't need to recount again.
- // But we always do it to keep the code simple and stupid.
- expression.ReHashCode(sf, sctx)
+ if changed {
+ expression.ReHashCode(sf, sctx)
+ }
  }()
  var expr *expression.Expression
  var tp types.EvalType
  switch sf.FuncName.L {
  case ast.EQ, ast.LT, ast.LE, ast.GT, ast.GE:
  for candidateExpr, column := range exprToColumn {
- tryToSubstituteExpr(&sf.GetArgs()[1], sessionCtx, candidateExpr, sf.GetArgs()[0].GetType().EvalType(), schema, column)
+ collectChanged(tryToSubstituteExpr(&sf.GetArgs()[1], sessionCtx, candidateExpr, sf.GetArgs()[0].GetType().EvalType(), schema, column))
  }
  for candidateExpr, column := range exprToColumn {
- tryToSubstituteExpr(&sf.GetArgs()[0], sessionCtx, candidateExpr, sf.GetArgs()[1].GetType().EvalType(), schema, column)
+ collectChanged(tryToSubstituteExpr(&sf.GetArgs()[0], sessionCtx, candidateExpr, sf.GetArgs()[1].GetType().EvalType(), schema, column))
  }
  case ast.In:
  expr = &sf.GetArgs()[0]
@@ -115,21 +130,22 @@ func substituteExpression(cond expression.Expression, sctx *stmtctx.StatementCon
  }
  if canSubstitute {
  for candidateExpr, column := range exprToColumn {
- tryToSubstituteExpr(expr, sessionCtx, candidateExpr, tp, schema, column)
+ collectChanged(tryToSubstituteExpr(expr, sessionCtx, candidateExpr, tp, schema, column))
  }
  }
  case ast.Like:
  expr = &sf.GetArgs()[0]
  tp = sf.GetArgs()[1].GetType().EvalType()
  for candidateExpr, column := range exprToColumn {
- tryToSubstituteExpr(expr, sessionCtx, candidateExpr, tp, schema, column)
+ collectChanged(tryToSubstituteExpr(expr, sessionCtx, candidateExpr, tp, schema, column))
  }
  case ast.LogicOr, ast.LogicAnd:
- substituteExpression(sf.GetArgs()[0], sctx, sessionCtx, exprToColumn, schema)
- substituteExpression(sf.GetArgs()[1], sctx, sessionCtx, exprToColumn, schema)
+ collectChanged(substituteExpression(sf.GetArgs()[0], sctx, sessionCtx, exprToColumn, schema))
+ collectChanged(substituteExpression(sf.GetArgs()[1], sctx, sessionCtx, exprToColumn, schema))
  case ast.UnaryNot:
- substituteExpression(sf.GetArgs()[0], sctx, sessionCtx, exprToColumn, schema)
+ collectChanged(substituteExpression(sf.GetArgs()[0], sctx, sessionCtx, exprToColumn, schema))
  }
+ return changed
 }
 
 func (gc *gcSubstituter) substitute(ctx context.Context, lp LogicalPlan, exprToColumn ExprColumnMap) LogicalPlan {