diff --git a/executor/builder.go b/executor/builder.go
index 8fb430f113633..68af3a6bfd888 100644
--- a/executor/builder.go
+++ b/executor/builder.go
@@ -981,7 +981,7 @@ func (b *executorBuilder) buildProjBelowAgg(aggFuncs []*aggregation.AggFuncDesc,
 
 	return &ProjectionExec{
 		baseExecutor:  newBaseExecutor(b.ctx, expression.NewSchema(projSchemaCols...), projFromID, src),
-		evaluatorSuit: expression.NewEvaluatorSuit(projExprs),
+		evaluatorSuit: expression.NewEvaluatorSuite(projExprs, false),
 	}
 }
 
@@ -1112,7 +1112,7 @@ func (b *executorBuilder) buildProjection(v *plannercore.PhysicalProjection) Exe
 	e := &ProjectionExec{
 		baseExecutor:     newBaseExecutor(b.ctx, v.Schema(), v.ExplainID(), childExec),
 		numWorkers:       b.ctx.GetSessionVars().ProjectionConcurrency,
-		evaluatorSuit:    expression.NewEvaluatorSuit(v.Exprs),
+		evaluatorSuit:    expression.NewEvaluatorSuite(v.Exprs, v.AvoidColumnEvaluator),
 		calculateNoDelay: v.CalculateNoDelay,
 	}
 
diff --git a/executor/executor_test.go b/executor/executor_test.go
index f60689229c631..311df7dcfffbf 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -1044,6 +1044,13 @@ func (s *testSuite) TestUnion(c *C) {
 	tk.MustExec("create table t(a int, b int)")
 	tk.MustExec("insert into t value(1 ,2)")
 	tk.MustQuery("select a, b from (select a, 0 as d, b from t union all select a, 0 as d, b from t) test;").Check(testkit.Rows("1 2", "1 2"))
+
+	// #issue 8141
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1(a int, b int)")
+	tk.MustExec("insert into t1 value(1,2),(1,1),(2,2),(2,2),(3,2),(3,2)")
+	tk.MustExec("set @@tidb_max_chunk_size=2;")
+	tk.MustQuery("select count(*) from (select a as c, a as d from t1 union all select a, b from t1) t;").Check(testkit.Rows("12"))
 }
 
 func (s *testSuite) TestNeighbouringProj(c *C) {
diff --git a/executor/projection.go b/executor/projection.go
index dce2709f1271b..4b3506c999cba 100644
--- a/executor/projection.go
+++ b/executor/projection.go
@@ -49,7 +49,7 @@ type projectionOutput struct {
 type ProjectionExec struct {
 	baseExecutor
 
-	evaluatorSuit    *expression.EvaluatorSuit
+	evaluatorSuit    *expression.EvaluatorSuite
 	calculateNoDelay bool
 
 	prepared    bool
@@ -295,7 +295,7 @@ func (f *projectionInputFetcher) run(ctx context.Context) {
 
 type projectionWorker struct {
 	sctx            sessionctx.Context
-	evaluatorSuit   *expression.EvaluatorSuit
+	evaluatorSuit   *expression.EvaluatorSuite
 	globalFinishCh  <-chan struct{}
 	inputGiveBackCh chan<- *projectionInput
 
diff --git a/expression/evaluator.go b/expression/evaluator.go
index 84f2cc81627c8..d1ff7221b7d5c 100644
--- a/expression/evaluator.go
+++ b/expression/evaluator.go
@@ -64,36 +64,36 @@ func (e *defaultEvaluator) run(ctx sessionctx.Context, input, output *chunk.Chun
 	return nil
 }
 
-// EvaluatorSuit is responsible for the evaluation of a list of expressions.
+// EvaluatorSuite is responsible for the evaluation of a list of expressions.
 // It separates them to "column" and "other" expressions and evaluates "other"
 // expressions before "column" expressions.
-type EvaluatorSuit struct {
+type EvaluatorSuite struct {
 	*columnEvaluator  // Evaluator for column expressions.
 	*defaultEvaluator // Evaluator for other expressions.
 }
 
-// NewEvaluatorSuit creates an EvaluatorSuit to evaluate all the exprs.
-func NewEvaluatorSuit(exprs []Expression) *EvaluatorSuit {
-	e := &EvaluatorSuit{}
+// NewEvaluatorSuite creates an EvaluatorSuite to evaluate all the exprs.
+// avoidColumnEvaluator can be removed after column pool is supported.
+func NewEvaluatorSuite(exprs []Expression, avoidColumnEvaluator bool) *EvaluatorSuite {
+	e := &EvaluatorSuite{}
 
-	for i, expr := range exprs {
-		switch x := expr.(type) {
-		case *Column:
+	for i := 0; i < len(exprs); i++ {
+		if col, isCol := exprs[i].(*Column); isCol && !avoidColumnEvaluator {
 			if e.columnEvaluator == nil {
 				e.columnEvaluator = &columnEvaluator{inputIdxToOutputIdxes: make(map[int][]int)}
 			}
-			inputIdx, outputIdx := x.Index, i
+			inputIdx, outputIdx := col.Index, i
 			e.columnEvaluator.inputIdxToOutputIdxes[inputIdx] = append(e.columnEvaluator.inputIdxToOutputIdxes[inputIdx], outputIdx)
-		default:
-			if e.defaultEvaluator == nil {
-				e.defaultEvaluator = &defaultEvaluator{
-					outputIdxes: make([]int, 0, len(exprs)),
-					exprs:       make([]Expression, 0, len(exprs)),
-				}
+			continue
+		}
+		if e.defaultEvaluator == nil {
+			e.defaultEvaluator = &defaultEvaluator{
+				outputIdxes: make([]int, 0, len(exprs)),
+				exprs:       make([]Expression, 0, len(exprs)),
 			}
-			e.defaultEvaluator.exprs = append(e.defaultEvaluator.exprs, x)
-			e.defaultEvaluator.outputIdxes = append(e.defaultEvaluator.outputIdxes, i)
 		}
+		e.defaultEvaluator.exprs = append(e.defaultEvaluator.exprs, exprs[i])
+		e.defaultEvaluator.outputIdxes = append(e.defaultEvaluator.outputIdxes, i)
 	}
 
 	if e.defaultEvaluator != nil {
@@ -102,14 +102,14 @@ func NewEvaluatorSuit(exprs []Expression) *EvaluatorSuit {
 	return e
 }
 
-// Vectorizable checks whether this EvaluatorSuit can use vectorizd execution mode.
-func (e *EvaluatorSuit) Vectorizable() bool {
+// Vectorizable checks whether this EvaluatorSuite can use vectorizd execution mode.
+func (e *EvaluatorSuite) Vectorizable() bool {
 	return e.defaultEvaluator == nil || e.defaultEvaluator.vectorizable
 }
 
-// Run evaluates all the expressions hold by this EvaluatorSuit.
+// Run evaluates all the expressions hold by this EvaluatorSuite.
 // NOTE: "defaultEvaluator" must be evaluated before "columnEvaluator".
-func (e *EvaluatorSuit) Run(ctx sessionctx.Context, input, output *chunk.Chunk) error {
+func (e *EvaluatorSuite) Run(ctx sessionctx.Context, input, output *chunk.Chunk) error {
 	if e.defaultEvaluator != nil {
 		err := e.defaultEvaluator.run(ctx, input, output)
 		if err != nil {
diff --git a/planner/core/exhaust_physical_plans.go b/planner/core/exhaust_physical_plans.go
index dc102b0c34d08..3f8c36f512c8b 100644
--- a/planner/core/exhaust_physical_plans.go
+++ b/planner/core/exhaust_physical_plans.go
@@ -692,8 +692,9 @@ func (p *LogicalProjection) exhaustPhysicalPlans(prop *property.PhysicalProperty
 		return nil
 	}
 	proj := PhysicalProjection{
-		Exprs:            p.Exprs,
-		CalculateNoDelay: p.calculateNoDelay,
+		Exprs:                p.Exprs,
+		CalculateNoDelay:     p.calculateNoDelay,
+		AvoidColumnEvaluator: p.avoidColumnEvaluator,
 	}.init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), newProp)
 	proj.SetSchema(p.schema)
 	return []PhysicalPlan{proj}
diff --git a/planner/core/logical_plan_builder.go b/planner/core/logical_plan_builder.go
index 6f95472269905..46b60897c2d85 100644
--- a/planner/core/logical_plan_builder.go
+++ b/planner/core/logical_plan_builder.go
@@ -677,7 +677,7 @@ func (b *planBuilder) buildProjection4Union(u *LogicalUnionAll) {
 			}
 		}
 		b.optFlag |= flagEliminateProjection
-		proj := LogicalProjection{Exprs: exprs}.init(b.ctx)
+		proj := LogicalProjection{Exprs: exprs, avoidColumnEvaluator: true}.init(b.ctx)
 		proj.SetSchema(u.schema.Clone())
 		proj.SetChildren(child)
 		u.children[childID] = proj
diff --git a/planner/core/logical_plans.go b/planner/core/logical_plans.go
index 9caedb2b3cea1..99967e12e5f71 100644
--- a/planner/core/logical_plans.go
+++ b/planner/core/logical_plans.go
@@ -185,6 +185,13 @@ type LogicalProjection struct {
 	// Currently it is "true" only when the current sql query is a "DO" statement.
 	// See "https://dev.mysql.com/doc/refman/5.7/en/do.html" for more detail.
 	calculateNoDelay bool
+
+	// avoidColumnRef is a temporary variable which is ONLY used to avoid
+	// building columnEvaluator for the expressions of Projection which is
+	// built by buildProjection4Union.
+	// This can be removed after column pool being supported.
+	// Related issue: TiDB#8141(https://github.com/pingcap/tidb/issues/8141)
+	avoidColumnEvaluator bool
 }
 
 func (p *LogicalProjection) extractCorrelatedCols() []*expression.CorrelatedColumn {
diff --git a/planner/core/physical_plans.go b/planner/core/physical_plans.go
index 53e80699f78ef..48ceea5f48001 100644
--- a/planner/core/physical_plans.go
+++ b/planner/core/physical_plans.go
@@ -170,8 +170,9 @@ func (ts *PhysicalTableScan) IsPartition() (bool, int64) {
 type PhysicalProjection struct {
 	physicalSchemaProducer
 
-	Exprs            []expression.Expression
-	CalculateNoDelay bool
+	Exprs                []expression.Expression
+	CalculateNoDelay     bool
+	AvoidColumnEvaluator bool
 }
 
 // PhysicalTopN is the physical operator of topN.