fixed sequencer issue

go.mod

@@ -28,7 +28,7 @@ require (
 	github.com/viant/parsly v0.3.3
 	github.com/viant/pgo v0.11.0
 	github.com/viant/scy v0.24.0
-	github.com/viant/sqlx v0.21.0
+	github.com/viant/sqlx v0.22.1-0.20260326175456-cec446e28372
 	github.com/viant/structql v0.5.4
 	github.com/viant/toolbox v0.37.0
 	github.com/viant/velty v0.4.0

go.sum

@@ -1196,8 +1196,8 @@ github.com/viant/scy v0.24.0 h1:KAC3IUARkQxTNSuwBK2YhVBJMOOLN30YaLKHbbuSkMU=
 github.com/viant/scy v0.24.0/go.mod h1:7uNRS67X45YN+JqTLCcMEhehffVjqrejULEDln9p0Ao=
 github.com/viant/sqlparser v0.11.1-0.20260224194657-0470849e3588 h1:bnVgWzZzuz2pTa54e7YozHjYNFSapfU3MSklyMkO+Ag=
 github.com/viant/sqlparser v0.11.1-0.20260224194657-0470849e3588/go.mod h1:2QRGiGZYk2/pjhORGG1zLVQ9JO+bXFhqIVi31mkCRPg=
-github.com/viant/sqlx v0.21.0 h1:Lx5KXmzfSjSvZZX5P0Ua9kFGvAmCxAjLOPe9pQA7VmY=
-github.com/viant/sqlx v0.21.0/go.mod h1:woTOwNiqvt6SqkI+5nyzlixcRTTV0IvLZUTberqb8mo=
+github.com/viant/sqlx v0.22.1-0.20260326175456-cec446e28372 h1:5qW+4AbQ8YA0MsyoUx3uaNgTHl52F0JBoC2vsdwKXIM=
+github.com/viant/sqlx v0.22.1-0.20260326175456-cec446e28372/go.mod h1:woTOwNiqvt6SqkI+5nyzlixcRTTV0IvLZUTberqb8mo=
 github.com/viant/structology v0.9.0 h1:ibR/XmdQ3+/4XW3JK+pXRqugSnxJOm2bmIvbQ0hqztY=
 github.com/viant/structology v0.9.0/go.mod h1:AAFeViwniqua61sTKdOz/zlbLpN5vE4OVhDoiZJaMgA=
 github.com/viant/structql v0.5.4 h1:bMdcOpzU8UMoe5OBcyJVRxLAndvU1oj3ysvPUgBckCI=

service/executor/sequencer/service.go

@@ -32,10 +32,13 @@ func (s *Service) next(table string, any interface{}, selector string) error {
 	if err != nil || emptyRecordCount == 0 {
 		return err
 	}
-	record, err := aWalker.Leaf(any)
+	record, err := aWalker.EmptyLeaf(any)
 	if err != nil {
 		return err
 	}
+	if record == nil {
+		return nil
+	}
 	inserter, err := insert.New(s.ctx, s.db, table)
 	if err != nil {
 		return err

service/executor/sequencer/walker.go

@@ -19,6 +19,11 @@ func (w *Walker) Leaf(value interface{}) (interface{}, error) {
 	return w.leaf(w.root, value)
 }
 
+// EmptyLeaf returns the first record whose leaf selector currently has a zero value.
+func (w *Walker) EmptyLeaf(value interface{}) (interface{}, error) {
+	return w.emptyLeaf(w.root, value)
+}
+
 // Allocate allocate sequence
 func (w *Walker) Allocate(value interface{}, seq *Sequence) error {
 	return w.allocate(w.root, value, seq)
@@ -106,7 +111,7 @@ func (w *Walker) leaf(aNode *node, value interface{}) (interface{}, error) {
 		return value, nil
 	case nodeKindArray:
 		sliceLen := aNode.xSlice.Len(ptr)
-		for i := 0; i < sliceLen; {
+		for i := 0; i < sliceLen; i++ {
 			item := aNode.xSlice.ValuePointerAt(ptr, i)
 			first, err := w.leaf(aNode.children, item)
 			if err != nil {
@@ -121,6 +126,40 @@ func (w *Walker) leaf(aNode *node, value interface{}) (interface{}, error) {
 	return item, nil
 }
 
+func (w *Walker) emptyLeaf(aNode *node, value interface{}) (interface{}, error) {
+	ptr := xunsafe.AsPointer(value)
+	var item interface{}
+	switch aNode.kind {
+	case nodeKindObject:
+		item = aNode.xField.Interface(ptr)
+		return w.emptyLeaf(aNode.children, item)
+	case nodeKindLeaf:
+		item = aNode.xField.Addr(ptr)
+		intPtr, err := int64Ptr(item)
+		if err != nil {
+			return nil, err
+		}
+		if *intPtr == 0 {
+			return value, nil
+		}
+		return nil, nil
+	case nodeKindArray:
+		sliceLen := aNode.xSlice.Len(ptr)
+		for i := 0; i < sliceLen; i++ {
+			item := aNode.xSlice.ValuePointerAt(ptr, i)
+			first, err := w.emptyLeaf(aNode.children, item)
+			if err != nil {
+				return nil, err
+			}
+			if first != nil {
+				return first, nil
+			}
+		}
+		return nil, nil
+	}
+	return item, nil
+}
+
 func int64Ptr(value interface{}) (*int64, error) {
 	switch actual := value.(type) {
 	case *int, *uint, uint64:

service/executor/sequencer/walker_test.go

@@ -152,3 +152,68 @@ func TestWalker_Leaf(t *testing.T) {
 	}
 
 }
+
+func TestWalker_EmptyLeaf(t *testing.T) {
+	type Foo struct {
+		ID   int
+		Name string
+	}
+
+	type Bar struct {
+		ID   int
+		Foos []Foo
+	}
+
+	testCases := []struct {
+		description string
+		value       interface{}
+		selectors   []string
+		expect      interface{}
+	}{
+		{
+			description: "nested selector returns first empty leaf owner",
+			value: []*Bar{
+				{
+					ID: 1,
+					Foos: []Foo{
+						{ID: 10, Name: "keep"},
+						{ID: 0, Name: "allocate-me"},
+					},
+				},
+			},
+			selectors: []string{"Foos", "ID"},
+			expect:    &Foo{ID: 0, Name: "allocate-me"},
+		},
+		{
+			description: "slice selector skips non-empty ids",
+			value: []*Foo{
+				{ID: 101, Name: "already-set"},
+				{ID: 0, Name: "needs-id"},
+				{ID: 0, Name: "also-needs-id"},
+			},
+			selectors: []string{"ID"},
+			expect:    &Foo{ID: 0, Name: "needs-id"},
+		},
+		{
+			description: "returns nil when there are no empty ids",
+			value: []*Foo{
+				{ID: 101, Name: "already-set"},
+				{ID: 102, Name: "also-set"},
+			},
+			selectors: []string{"ID"},
+			expect:    nil,
+		},
+	}
+
+	for _, testCase := range testCases {
+		aWalker, err := NewWalker(testCase.value, testCase.selectors)
+		if !assert.Nil(t, err, testCase.description) {
+			continue
+		}
+		actual, err := aWalker.EmptyLeaf(testCase.value)
+		if !assert.Nil(t, err, testCase.description) {
+			continue
+		}
+		assert.EqualValues(t, testCase.expect, actual, testCase.description)
+	}
+}