fix downstream recursion

api/src/main/java/marquez/db/ColumnLineageDao.java

@@ -99,19 +99,28 @@ void doUpsertColumnLineageRow(
   @SqlQuery(
       """
           WITH RECURSIVE
+            column_lineage_latest AS (
+                SELECT DISTINCT ON (output_dataset_field_uuid, input_dataset_field_uuid) *
+                FROM column_lineage
+                WHERE created_at <= :createdAtUntil
+                ORDER BY output_dataset_field_uuid, input_dataset_field_uuid, updated_at DESC, updated_at
+            ),
             dataset_fields_view AS (
               SELECT d.namespace_name as namespace_name, d.name as dataset_name, df.name as field_name, df.type, df.uuid
               FROM dataset_fields df
               INNER JOIN datasets_view d ON d.uuid = df.dataset_uuid
             ),
             column_lineage_recursive AS (
               (
-                SELECT DISTINCT ON (output_dataset_field_uuid, input_dataset_field_uuid) *, 0 as depth
-                FROM column_lineage
-                WHERE output_dataset_field_uuid IN (<datasetFieldUuids>) AND created_at <= :createdAtUntil
-                ORDER BY output_dataset_field_uuid, input_dataset_field_uuid, updated_at DESC, updated_at
+                SELECT
+                  *,
+                  0 as depth,
+                  false as is_cycle,
+                  ARRAY[ROW(output_dataset_field_uuid, input_dataset_field_uuid)] as path -- path and is_cycle mechanism as describe here https://www.postgresql.org/docs/current/queries-with.html (CYCLE clause not available in postgresql 12)
+                FROM column_lineage_latest
+                WHERE output_dataset_field_uuid IN (<datasetFieldUuids>)
               )
-              UNION
+              UNION ALL
               SELECT
                 adjacent_node.output_dataset_version_uuid,
                 adjacent_node.output_dataset_field_uuid,
@@ -121,27 +130,31 @@ WHERE output_dataset_field_uuid IN (<datasetFieldUuids>) AND created_at <= :crea
                 adjacent_node.transformation_type,
                 adjacent_node.created_at,
                 adjacent_node.updated_at,
-                node.depth + 1 as depth
-              FROM column_lineage adjacent_node, column_lineage_recursive node
+                node.depth + 1 as depth,
+                ROW(adjacent_node.input_dataset_field_uuid, adjacent_node.output_dataset_field_uuid) = ANY(path) as is_cycle,
+                path || ROW(adjacent_node.input_dataset_field_uuid, adjacent_node.output_dataset_field_uuid) as path
+              FROM column_lineage_latest adjacent_node, column_lineage_recursive node
               WHERE (
                 (node.input_dataset_field_uuid = adjacent_node.output_dataset_field_uuid) --upstream lineage
                 OR (:withDownstream AND adjacent_node.input_dataset_field_uuid = node.output_dataset_field_uuid) --optional downstream lineage
               )
               AND node.depth < :depth
+              AND NOT is_cycle
             )
             SELECT
                 output_fields.namespace_name,
                 output_fields.dataset_name,
                 output_fields.field_name,
                 output_fields.type,
-                ARRAY_AGG(ARRAY[input_fields.namespace_name, input_fields.dataset_name, input_fields.field_name]) AS inputFields,
+                ARRAY_AGG(DISTINCT ARRAY[input_fields.namespace_name, input_fields.dataset_name, input_fields.field_name]) AS inputFields,
                 clr.transformation_description,
                 clr.transformation_type,
                 clr.created_at,
                 clr.updated_at
             FROM column_lineage_recursive clr
             INNER JOIN dataset_fields_view output_fields ON clr.output_dataset_field_uuid = output_fields.uuid -- hidden datasets will be filtered
             LEFT JOIN dataset_fields_view input_fields ON clr.input_dataset_field_uuid = input_fields.uuid
+            WHERE NOT clr.is_cycle
             GROUP BY
                 output_fields.namespace_name,
                 output_fields.dataset_name,

api/src/main/java/marquez/service/ColumnLineageService.java

@@ -71,7 +71,7 @@ private Lineage toLineage(Set<ColumnLineageNodeData> lineageNodeData) {
                               DatasetFieldId.of(i.getNamespace(), i.getDataset(), i.getField())))
                   .forEach(
                       inputNodeId -> {
-                        graphNodes.put(inputNodeId, Node.datasetField().id(inputNodeId));
+                        graphNodes.putIfAbsent(inputNodeId, Node.datasetField().id(inputNodeId));
                         Optional.ofNullable(outEdges.get(inputNodeId))
                             .ifPresentOrElse(
                                 nodeEdges -> nodeEdges.add(nodeId),

api/src/test/java/marquez/service/ColumnLineageServiceTest.java

@@ -318,6 +318,15 @@ public void testGetLineageWithDownstream() {
                 .filter(c -> c.getId().asDatasetFieldId().getFieldName().getValue().equals("col_d"))
                 .findAny())
         .isPresent();
+
+    ColumnLineageNodeData nodeData_C =
+        (ColumnLineageNodeData)
+            lineage.getGraph().stream()
+                .filter(c -> c.getId().asDatasetFieldId().getFieldName().getValue().equals("col_c"))
+                .findAny()
+                .get()
+                .getData();
+    assertThat(nodeData_C.getInputFields()).hasSize(2);
   }
 
   @Test