diff --git a/go/test/endtoend/vtgate/gen4/gen4_test.go b/go/test/endtoend/vtgate/gen4/gen4_test.go
index de18e1aa257..bb350f7632a 100644
--- a/go/test/endtoend/vtgate/gen4/gen4_test.go
+++ b/go/test/endtoend/vtgate/gen4/gen4_test.go
@@ -196,6 +196,28 @@ func TestSubQueries(t *testing.T) {
 	assertMatches(t, conn, `select (select id from t2 order by id limit 1) from t2 order by id limit 2`, `[[INT64(1)] [INT64(1)]]`)
 }
 
+func TestPlannerWarning(t *testing.T) {
+	ctx := context.Background()
+	conn, err := mysql.Connect(ctx, &vtParams)
+	require.NoError(t, err)
+	defer conn.Close()
+
+	// straight_join query
+	_ = checkedExec(t, conn, `select 1 from t1 straight_join t2 on t1.id = t2.id`)
+	assertMatches(t, conn, `show warnings`, `[[VARCHAR("Warning") UINT16(1235) VARCHAR("straight join is converted to normal join")]]`)
+
+	// execute same query again.
+	_ = checkedExec(t, conn, `select 1 from t1 straight_join t2 on t1.id = t2.id`)
+	assertMatches(t, conn, `show warnings`, `[[VARCHAR("Warning") UINT16(1235) VARCHAR("straight join is converted to normal join")]]`)
+
+	// random query to reset the warning.
+	_ = checkedExec(t, conn, `select 1 from t1`)
+
+	// execute same query again.
+	_ = checkedExec(t, conn, `select 1 from t1 straight_join t2 on t1.id = t2.id`)
+	assertMatches(t, conn, `show warnings`, `[[VARCHAR("Warning") UINT16(1235) VARCHAR("straight join is converted to normal join")]]`)
+}
+
 func assertMatches(t *testing.T, conn *mysql.Conn, query, expected string) {
 	t.Helper()
 	qr := checkedExec(t, conn, query)
diff --git a/go/vt/vtgate/executor_select_test.go b/go/vt/vtgate/executor_select_test.go
index e471b91147c..2e33f3930cc 100644
--- a/go/vt/vtgate/executor_select_test.go
+++ b/go/vt/vtgate/executor_select_test.go
@@ -2675,3 +2675,36 @@ func TestSelectScatterFails(t *testing.T) {
 	_, err = executorExecSession(executor, "select /*vt+ ALLOW_SCATTER */ id from user", nil, sess)
 	require.NoError(t, err)
 }
+
+func TestGen4SelectStraightJoin(t *testing.T) {
+	executor, sbc1, _, _ := createExecutorEnv()
+	executor.normalize = true
+	*plannerVersion = "gen4"
+	defer func() {
+		// change it back to v3
+		*plannerVersion = "v3"
+	}()
+
+	session := NewSafeSession(&vtgatepb.Session{TargetString: "TestExecutor"})
+	query := "select u.id from user u straight_join user2 u2 on u.id = u2.id"
+	_, err := executor.Execute(context.Background(),
+		"TestGen4SelectStraightJoin",
+		session,
+		query, map[string]*querypb.BindVariable{},
+	)
+	require.NoError(t, err)
+	wantQueries := []*querypb.BoundQuery{
+		{
+			Sql:           "select u.id from `user` as u, user2 as u2 where u.id = u2.id",
+			BindVariables: map[string]*querypb.BindVariable{},
+		},
+	}
+	wantWarnings := []*querypb.QueryWarning{
+		{
+			Code:    1235,
+			Message: "straight join is converted to normal join",
+		},
+	}
+	utils.MustMatch(t, wantQueries, sbc1.Queries)
+	utils.MustMatch(t, wantWarnings, session.Warnings)
+}
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..a804f972b22 100644
--- a/go/vt/vtgate/planbuilder/gen4_planner.go
+++ b/go/vt/vtgate/planbuilder/gen4_planner.go
@@ -78,6 +78,9 @@ func gen4planSQLCalcFoundRows(vschema ContextVSchema, sel *sqlparser.Select, que
 	if err != nil {
 		return nil, err
 	}
+	// record any warning as planner warning.
+	vschema.PlannerWarning(semTable.Warning)
+
 	plan, err := buildSQLCalcFoundRowsPlan(query, sel, reservedVars, vschema, planSelectGen4)
 	if err != nil {
 		return nil, err
@@ -120,6 +123,8 @@ func newBuildSelectPlan(selStmt sqlparser.SelectStatement, reservedVars *sqlpars
 	if err != nil {
 		return nil, err
 	}
+	// record any warning as planner warning.
+	vschema.PlannerWarning(semTable.Warning)
 
 	err = queryRewrite(semTable, reservedVars, selStmt)
 	if err != nil {
diff --git a/go/vt/vtgate/planbuilder/horizon_planning.go b/go/vt/vtgate/planbuilder/horizon_planning.go
index 490bb5acbb4..794c7894bc6 100644
--- a/go/vt/vtgate/planbuilder/horizon_planning.go
+++ b/go/vt/vtgate/planbuilder/horizon_planning.go
@@ -259,11 +259,12 @@ func pushProjection(expr *sqlparser.AliasedExpr, plan logicalPlan, semTable *sem
 		}
 		return 0, false, vterrors.Errorf(vtrpcpb.Code_INTERNAL, "cannot push projections in ordered aggregates")
 	case *vindexFunc:
+		colsBefore := len(node.eVindexFunc.Cols)
 		i, err := node.SupplyProjection(expr, reuseCol)
 		if err != nil {
 			return 0, false, err
 		}
-		return i, true, nil
+		return i /* col added */, len(node.eVindexFunc.Cols) > colsBefore, nil
 	case *limit:
 		return pushProjection(expr, node.input, semTable, inner, reuseCol)
 	case *distinct:
@@ -629,9 +630,10 @@ func (hp *horizonPlanning) planOrderBy(ctx *planningContext, orderExprs []abstra
 		plan.input = newUnderlyingPlan
 		return plan, nil
 	case *simpleProjection:
-		return hp.createMemorySortPlan(ctx, plan, orderExprs)
+		return hp.createMemorySortPlan(ctx, plan, orderExprs, true)
 	case *vindexFunc:
-		return nil, semantics.Gen4NotSupportedF("unsupported: ordering on vindex func")
+		// This is evaluated at VTGate only, so weight_string function cannot be used.
+		return hp.createMemorySortPlan(ctx, plan, orderExprs /* useWeightStr */, false)
 	default:
 		return nil, vterrors.Errorf(vtrpcpb.Code_UNIMPLEMENTED, "ordering on complex query %T", plan)
 	}
@@ -760,7 +762,7 @@ func (hp *horizonPlanning) planOrderByForJoin(ctx *planningContext, orderExprs [
 		plan.Left = newLeft
 		return plan, nil
 	}
-	sortPlan, err := hp.createMemorySortPlan(ctx, plan, orderExprs)
+	sortPlan, err := hp.createMemorySortPlan(ctx, plan, orderExprs, true)
 	if err != nil {
 		return nil, err
 	}
@@ -807,7 +809,7 @@ func findExprInOrderedAggr(plan *orderedAggregate, order abstract.OrderBy) (int,
 	return 0, 0, false
 }
 
-func (hp *horizonPlanning) createMemorySortPlan(ctx *planningContext, plan logicalPlan, orderExprs []abstract.OrderBy) (logicalPlan, error) {
+func (hp *horizonPlanning) createMemorySortPlan(ctx *planningContext, plan logicalPlan, orderExprs []abstract.OrderBy, useWeightStr bool) (logicalPlan, error) {
 	primitive := &engine.MemorySort{}
 	ms := &memorySort{
 		resultsBuilder: resultsBuilder{
@@ -819,7 +821,11 @@ func (hp *horizonPlanning) createMemorySortPlan(ctx *planningContext, plan logic
 	}
 
 	for _, order := range orderExprs {
-		offset, weightStringOffset, added, err := wrapAndPushExpr(order.Inner.Expr, order.WeightStrExpr, plan, ctx.semTable)
+		wsExpr := order.WeightStrExpr
+		if !useWeightStr {
+			wsExpr = nil
+		}
+		offset, weightStringOffset, added, err := wrapAndPushExpr(order.Inner.Expr, wsExpr, plan, ctx.semTable)
 		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/planbuilder/testdata/memory_sort_cases.txt b/go/vt/vtgate/planbuilder/testdata/memory_sort_cases.txt
index 761e3689b83..d1a32f7f0ea 100644
--- a/go/vt/vtgate/planbuilder/testdata/memory_sort_cases.txt
+++ b/go/vt/vtgate/planbuilder/testdata/memory_sort_cases.txt
@@ -706,6 +706,7 @@ Gen4 plan same as above
     ]
   }
 }
+Gen4 plan same as above
 
 # unary expression
 "select a from user order by binary a desc"
diff --git a/go/vt/vtgate/semantics/analyzer.go b/go/vt/vtgate/semantics/analyzer.go
index fd2ae5f8405..0dd65ebe7c0 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
@@ -74,7 +75,6 @@ func Analyze(statement sqlparser.SelectStatement, currentDb string, si SchemaInf
 	// Creation of the semantic table
 	semTable := analyzer.newSemTable(statement)
 
-	semTable.ProjectionErr = analyzer.projErr
 	return semTable, nil
 }
 
@@ -86,6 +86,7 @@ func (a analyzer) newSemTable(statement sqlparser.SelectStatement) *SemTable {
 		Tables:           a.tables.Tables,
 		selectScope:      a.scoper.rScope,
 		ProjectionErr:    a.projErr,
+		Warning:          a.warning,
 		Comments:         statement.GetComments(),
 		SubqueryMap:      a.binder.subqueryMap,
 		SubqueryRef:      a.binder.subqueryRef,
@@ -126,6 +127,8 @@ 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 ""