diff --git a/go/vt/vtgate/planbuilder/abstract/operator.go b/go/vt/vtgate/planbuilder/abstract/operator.go
index 8f2cfac35a8..001459ac039 100644
--- a/go/vt/vtgate/planbuilder/abstract/operator.go
+++ b/go/vt/vtgate/planbuilder/abstract/operator.go
@@ -109,8 +109,6 @@ func getOperatorFromTableExpr(tableExpr sqlparser.TableExpr, semTable *semantics
 				lhs, rhs = rhs, lhs
 			}
 			return &Join{LHS: lhs, RHS: rhs, LeftJoin: true, Predicate: tableExpr.Condition.On}, nil
-		case sqlparser.StraightJoinType:
-			return nil, semantics.Gen4NotSupportedF(tableExpr.Join.ToString())
 		default:
 			return nil, vterrors.Errorf(vtrpcpb.Code_UNIMPLEMENTED, "unsupported: %s", tableExpr.Join.ToString())
 		}
diff --git a/go/vt/vtgate/planbuilder/builder.go b/go/vt/vtgate/planbuilder/builder.go
index b9f62bb7469..468face549c 100644
--- a/go/vt/vtgate/planbuilder/builder.go
+++ b/go/vt/vtgate/planbuilder/builder.go
@@ -63,6 +63,9 @@ type ContextVSchema interface {
 	// that could become a problem if they move to a sharded keyspace
 	WarnUnshardedOnly(format string, params ...interface{})
 
+	// PlannerWarning records warning created during planning.
+	PlannerWarning(message string)
+
 	// ForeignKeyMode returns the foreign_key flag value
 	ForeignKeyMode() string
 }
diff --git a/go/vt/vtgate/planbuilder/gen4_planner.go b/go/vt/vtgate/planbuilder/gen4_planner.go
index d990bf3bba2..cf8a026c91f 100644
--- a/go/vt/vtgate/planbuilder/gen4_planner.go
+++ b/go/vt/vtgate/planbuilder/gen4_planner.go
@@ -78,6 +78,10 @@ func gen4planSQLCalcFoundRows(vschema ContextVSchema, sel *sqlparser.Select, que
 	if err != nil {
 		return nil, err
 	}
+	if semTable.Warning != "" {
+		// log it as planning warning.
+		vschema.PlannerWarning(semTable.Warning)
+	}
 	plan, err := buildSQLCalcFoundRowsPlan(query, sel, reservedVars, vschema, planSelectGen4)
 	if err != nil {
 		return nil, err
diff --git a/go/vt/vtgate/planbuilder/plan_test.go b/go/vt/vtgate/planbuilder/plan_test.go
index f65fca732e2..1f3953573a6 100644
--- a/go/vt/vtgate/planbuilder/plan_test.go
+++ b/go/vt/vtgate/planbuilder/plan_test.go
@@ -437,6 +437,9 @@ type vschemaWrapper struct {
 	version       PlannerVersion
 }
 
+func (vw *vschemaWrapper) PlannerWarning(_ string) {
+}
+
 func (vw *vschemaWrapper) ForeignKeyMode() string {
 	return "allow"
 }
diff --git a/go/vt/vtgate/planbuilder/testdata/from_cases.txt b/go/vt/vtgate/planbuilder/testdata/from_cases.txt
index aab055e22e7..de0cb57ff30 100644
--- a/go/vt/vtgate/planbuilder/testdata/from_cases.txt
+++ b/go/vt/vtgate/planbuilder/testdata/from_cases.txt
@@ -784,7 +784,7 @@ Gen4 plan same as above
   }
 }
 
-# Straight-join
+# Straight-join (Gen4 ignores the straight_join hint)
 "select m1.col from unsharded as m1 straight_join unsharded as m2"
 {
   "QueryType": "SELECT",
@@ -801,6 +801,21 @@ Gen4 plan same as above
     "Table": "unsharded"
   }
 }
+{
+  "QueryType": "SELECT",
+  "Original": "select m1.col from unsharded as m1 straight_join unsharded as m2",
+  "Instructions": {
+    "OperatorType": "Route",
+    "Variant": "SelectUnsharded",
+    "Keyspace": {
+      "Name": "main",
+      "Sharded": false
+    },
+    "FieldQuery": "select m1.col from unsharded as m1, unsharded as m2 where 1 != 1",
+    "Query": "select m1.col from unsharded as m1, unsharded as m2",
+    "Table": "unsharded"
+  }
+}
 
 # Three-way join
 "select user.col from user join unsharded as m1 join unsharded as m2"
diff --git a/go/vt/vtgate/semantics/analyzer.go b/go/vt/vtgate/semantics/analyzer.go
index fd2ae5f8405..5708095439e 100644
--- a/go/vt/vtgate/semantics/analyzer.go
+++ b/go/vt/vtgate/semantics/analyzer.go
@@ -42,6 +42,7 @@ type analyzer struct {
 	inProjection int
 
 	projErr error
+	warning string
 }
 
 // newAnalyzer create the semantic analyzer
@@ -75,6 +76,7 @@ func Analyze(statement sqlparser.SelectStatement, currentDb string, si SchemaInf
 	semTable := analyzer.newSemTable(statement)
 
 	semTable.ProjectionErr = analyzer.projErr
+	semTable.Warning = analyzer.warning
 	return semTable, nil
 }
 
@@ -126,6 +128,8 @@ func (a *analyzer) analyzeDown(cursor *sqlparser.Cursor) bool {
 		a.setError(err)
 		return true
 	}
+	// log any warn in rewriting.
+	a.warning = a.rewriter.warning
 
 	a.enterProjection(cursor)
 	// this is the visitor going down the tree. Returning false here would just not visit the children
diff --git a/go/vt/vtgate/semantics/early_rewriter.go b/go/vt/vtgate/semantics/early_rewriter.go
index 613d39c39a5..fcab3a63559 100644
--- a/go/vt/vtgate/semantics/early_rewriter.go
+++ b/go/vt/vtgate/semantics/early_rewriter.go
@@ -25,8 +25,9 @@ import (
 )
 
 type earlyRewriter struct {
-	scoper *scoper
-	clause string
+	scoper  *scoper
+	clause  string
+	warning string
 }
 
 func (r *earlyRewriter) down(cursor *sqlparser.Cursor) error {
@@ -59,6 +60,11 @@ func (r *earlyRewriter) down(cursor *sqlparser.Cursor) error {
 		if changed {
 			cursor.ReplaceAndRevisit(selExprs)
 		}
+	case *sqlparser.JoinTableExpr:
+		if node.Join == sqlparser.StraightJoinType {
+			node.Join = sqlparser.NormalJoinType
+			r.warning = "straight join is converted to normal join"
+		}
 	case *sqlparser.Order:
 		r.clause = "order clause"
 	case sqlparser.GroupBy:
diff --git a/go/vt/vtgate/semantics/semantic_state.go b/go/vt/vtgate/semantics/semantic_state.go
index 8c252c2b78a..c140c3b631f 100644
--- a/go/vt/vtgate/semantics/semantic_state.go
+++ b/go/vt/vtgate/semantics/semantic_state.go
@@ -90,6 +90,8 @@ type (
 		// ColumnEqualities is used to enable transitive closures
 		// if a == b and b == c then a == c
 		ColumnEqualities map[columnName][]sqlparser.Expr
+
+		Warning string
 	}
 
 	columnName struct {
diff --git a/go/vt/vtgate/vcursor_impl.go b/go/vt/vtgate/vcursor_impl.go
index a63a7697948..5f9b6ae2c3a 100644
--- a/go/vt/vtgate/vcursor_impl.go
+++ b/go/vt/vtgate/vcursor_impl.go
@@ -371,6 +371,7 @@ func (vc *vcursorImpl) TargetString() string {
 	return vc.safeSession.TargetString
 }
 
+// MaxBufferingRetries is to represent max retries on buffering.
 const MaxBufferingRetries = 3
 
 func (vc *vcursorImpl) ExecutePrimitive(primitive engine.Primitive, bindVars map[string]*querypb.BindVariable, wantfields bool) (*sqltypes.Result, error) {
@@ -746,7 +747,18 @@ func (vc *vcursorImpl) WarnUnshardedOnly(format string, params ...interface{}) {
 	}
 }
 
-// ForeignKey implements the VCursor interface
+// PlannerWarning implements the VCursor interface
+func (vc *vcursorImpl) PlannerWarning(message string) {
+	if message == "" {
+		return
+	}
+	vc.warnings = append(vc.warnings, &querypb.QueryWarning{
+		Code:    mysql.ERNotSupportedYet,
+		Message: message,
+	})
+}
+
+// ForeignKeyMode implements the VCursor interface
 func (vc *vcursorImpl) ForeignKeyMode() string {
 	if foreignKeyMode == nil {
 		return ""