enhance: add Slice func for go milvusclient column (#33836)

issue: #33419

Signed-off-by: ThreadDao <yufen.zong@zilliz.com>

client/column/array.go

@@ -47,6 +47,21 @@ func (c *ColumnVarCharArray) Len() int {
 	return len(c.values)
 }
 
+func (c *ColumnVarCharArray) Slice(start, end int) Column {
+	l := c.Len()
+	if start > l {
+		start = l
+	}
+	if end == -1 || end > l {
+		end = l
+	}
+	return &ColumnVarCharArray{
+		ColumnBase: c.ColumnBase,
+		name:       c.name,
+		values:     c.values[start:end],
+	}
+}
+
 // Get returns value at index as interface{}.
 func (c *ColumnVarCharArray) Get(idx int) (interface{}, error) {
 	var r []string // use default value

client/column/columns.go

@@ -32,6 +32,7 @@ type Column interface {
 	Name() string
 	Type() entity.FieldType
 	Len() int
+	Slice(int, int) Column
 	FieldData() *schemapb.FieldData
 	AppendValue(interface{}) error
 	Get(int) (interface{}, error)

client/column/json.go

@@ -53,6 +53,21 @@ func (c *ColumnJSONBytes) Len() int {
 	return len(c.values)
 }
 
+func (c *ColumnJSONBytes) Slice(start, end int) Column {
+	l := c.Len()
+	if start > l {
+		start = l
+	}
+	if end == -1 || end > l {
+		end = l
+	}
+	return &ColumnJSONBytes{
+		ColumnBase: c.ColumnBase,
+		name:       c.name,
+		values:     c.values[start:end],
+	}
+}
+
 // Get returns value at index as interface{}.
 func (c *ColumnJSONBytes) Get(idx int) (interface{}, error) {
 	if idx < 0 || idx > c.Len() {