feat: lateral column alias reference (#507)

sqllineage/core/holders.py

@@ -144,7 +144,7 @@ def expand_wildcard(self, metadata_provider: MetaDataProvider) -> None:
             for column in self.write_columns:
                 if column.raw_name == "*":
                     tgt_wildcard = column
-                    for src_wildcard in self._get_source_columns(tgt_wildcard):
+                    for src_wildcard in self.get_source_columns(tgt_wildcard):
                         if source_table := src_wildcard.parent:
                             src_table_columns = []
                             if isinstance(source_table, SubQuery):
@@ -169,7 +169,7 @@ def _get_target_table(self) -> Optional[Union[SubQuery, Table]]:
             table = next(iter(write_only))
         return table
 
-    def _get_source_columns(self, node: Column) -> List[Column]:
+    def get_source_columns(self, node: Column) -> List[Column]:
         return [
             src
             for (src, tgt, edge_type) in self.graph.in_edges(nbunch=node, data="type")

sqllineage/core/models.py

@@ -147,15 +147,15 @@ def __init__(self, name: str, **kwargs):
         """
         self._parent: Set[Union[Path, Table, SubQuery]] = set()
         self.raw_name = escape_identifier_name(name)
-        self.source_columns = (
+        self.source_columns = [
             (
                 escape_identifier_name(raw_name),
                 escape_identifier_name(qualifier) if qualifier is not None else None,
             )
             for raw_name, qualifier in kwargs.pop(
                 "source_columns", ((self.raw_name, None),)
             )
-        )
+        ]
 
     def __str__(self):
         return (

sqllineage/core/parser/__init__.py

@@ -25,8 +25,17 @@ def end_of_query_cleanup(self, holder: SubQueryLineageHolder) -> None:
                 if len(holder.write) > 1:
                     raise SQLLineageException
                 tgt_tbl = list(holder.write)[0]
+                lateral_aliases = set()
                 for idx, tgt_col in enumerate(col_grp):
                     tgt_col.parent = tgt_tbl
+                    if idx + 1 < len(col_grp) and isinstance(tgt_tbl, SubQuery):
+                        for _, lateral_alias_ref in enumerate(col_grp, idx + 1):
+                            if any(
+                                src_col[0] == tgt_col.raw_name
+                                for src_col in lateral_alias_ref.source_columns
+                            ):
+                                lateral_aliases.add(tgt_col.raw_name)
+                                break
                     for src_col in tgt_col.to_source_columns(
                         self.get_alias_mapping_from_table_group(tbl_grp, holder)
                     ):
@@ -37,6 +46,25 @@ def end_of_query_cleanup(self, holder: SubQueryLineageHolder) -> None:
                             # for invalid query: create view test (col3, col4) select col1 as col2 from tab,
                             # when the length doesn't match, we fall back to default behavior
                             tgt_col = write_columns[idx]
+                        if isinstance(tgt_tbl, SubQuery):
+                            is_lateral_alias_ref = False
+                            for wc in holder.write_columns:
+                                if wc.raw_name == "*":
+                                    continue
+                                if (
+                                    src_col.raw_name == wc.raw_name
+                                    and src_col.raw_name in lateral_aliases
+                                ):
+                                    is_lateral_alias_ref = True
+                                    for lateral_alias_col in holder.get_source_columns(
+                                        wc
+                                    ):
+                                        holder.add_column_lineage(
+                                            lateral_alias_col, tgt_col
+                                        )
+                                    break
+                            if is_lateral_alias_ref:
+                                continue
                         holder.add_column_lineage(src_col, tgt_col)
 
     @classmethod

tests/sql/column/test_column_select_lateral_alias_ref.py

@@ -0,0 +1,70 @@
+from sqllineage.utils.entities import ColumnQualifierTuple
+from ...helpers import assert_column_lineage_equal
+
+
+def test_column_lateral_ref():
+    sql = """
+    insert into public.tgt_tbl1
+    select
+        sq.name
+    from
+        (
+            select
+                id || name as alias1,
+                alias1 || email as name
+            from
+                public.src_tbl1
+        ) as sq
+    """
+    assert_column_lineage_equal(
+        sql,
+        [
+            (
+                ColumnQualifierTuple("id", "public.src_tbl1"),
+                ColumnQualifierTuple("name", "public.tgt_tbl1"),
+            ),
+            (
+                ColumnQualifierTuple("name", "public.src_tbl1"),
+                ColumnQualifierTuple("name", "public.tgt_tbl1"),
+            ),
+            (
+                ColumnQualifierTuple("email", "public.src_tbl1"),
+                ColumnQualifierTuple("name", "public.tgt_tbl1"),
+            ),
+        ],
+    )
+
+    sql = """
+    insert into public.tgt_tbl1
+    select
+        sq.name
+    from
+        (
+            select
+                st1.id || st1.name as alias1,
+                alias1 || st2.email as name
+            from
+                public.src_tbl1 as st1
+                join
+                    public.src_tbl2 as st2
+                on
+                    st1.id = st2.id
+        ) as sq
+    """
+    assert_column_lineage_equal(
+        sql,
+        [
+            (
+                ColumnQualifierTuple("id", "public.src_tbl1"),
+                ColumnQualifierTuple("name", "public.tgt_tbl1"),
+            ),
+            (
+                ColumnQualifierTuple("name", "public.src_tbl1"),
+                ColumnQualifierTuple("name", "public.tgt_tbl1"),
+            ),
+            (
+                ColumnQualifierTuple("email", "public.src_tbl2"),
+                ColumnQualifierTuple("name", "public.tgt_tbl1"),
+            ),
+        ],
+    )