Spanner fixes

internal/server/spanner/golden/query_builder/get_node_edges_first_page_chain.sql

@@ -3,8 +3,14 @@
 			m.subject_id IN ('dc/g/UN'))<-[e:Edge
 		WHERE
 			e.predicate = 'specializationOf']-{1,10}(n:Node)
-		RETURN
+		RETURN DISTINCT
 			m.subject_id,
+			n.subject_id AS value
+		NEXT MATCH (n)
+		WHERE
+		  n.subject_id = value
+		RETURN
+		  subject_id,
 			'specializationOf+' AS predicate,
 			'' AS provenance,
 			n.value,

internal/server/spanner/golden/query_builder/get_node_edges_in_chain.sql

@@ -3,8 +3,14 @@
 			m.subject_id IN ('dc/g/Farm_FarmInventoryStatus'))<-[e:Edge
 		WHERE
 			e.predicate = 'specializationOf']-{1,10}(n:Node)
-		RETURN
+		RETURN DISTINCT
 			m.subject_id,
+			n.subject_id AS value
+		NEXT MATCH (n)
+		WHERE
+		  n.subject_id = value
+		RETURN
+		  subject_id,
 			'specializationOf+' AS predicate,
 			'' AS provenance,
 			n.value,

internal/server/spanner/golden/query_builder/get_node_edges_out_chain.sql

@@ -3,8 +3,14 @@
 			m.subject_id IN ('dc/g/Person_Gender'))-[e:Edge
 		WHERE
 			e.predicate = 'specializationOf']->{1,10}(n:Node)
-		RETURN
+		RETURN DISTINCT
 			m.subject_id,
+			n.subject_id AS value
+		NEXT MATCH (n)
+		WHERE
+		  n.subject_id = value
+		RETURN
+		  subject_id,
 			'specializationOf+' AS predicate,
 			'' AS provenance,
 			n.value,

internal/server/spanner/golden/query_builder/get_node_edges_second_page_chain.sql

@@ -3,8 +3,14 @@
 			m.subject_id IN ('dc/g/UN'))<-[e:Edge
 		WHERE
 			e.predicate = 'specializationOf']-{1,10}(n:Node)
-		RETURN
+		RETURN DISTINCT
 			m.subject_id,
+			n.subject_id AS value
+		NEXT MATCH (n)
+		WHERE
+		  n.subject_id = value
+		RETURN
+		  subject_id,
 			'specializationOf+' AS predicate,
 			'' AS provenance,
 			n.value,

internal/server/spanner/golden/query_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"path"
 	"runtime"
+	"sort"
 	"testing"
 
 	"github.com/datacommonsorg/mixer/internal/server/spanner"
@@ -101,7 +102,12 @@ func TestGetObservations(t *testing.T) {
 		goldenFile := c.golden + ".json"
 
 		runQueryGoldenTest(t, goldenFile, func(ctx context.Context) (interface{}, error) {
-			return client.GetObservations(ctx, c.variables, c.entities)
+			actual, err := client.GetObservations(ctx, c.variables, c.entities)
+			if err != nil {
+				return nil, err
+			}
+			sortObservations(actual)
+			return actual, nil
 		})
 	}
 }
@@ -118,7 +124,12 @@ func TestGetObservationsContainedInPlace(t *testing.T) {
 		goldenFile := c.golden + ".json"
 
 		runQueryGoldenTest(t, goldenFile, func(ctx context.Context) (interface{}, error) {
-			return client.GetObservationsContainedInPlace(ctx, c.variables, c.containedInPlace)
+			actual, err := client.GetObservationsContainedInPlace(ctx, c.variables, c.containedInPlace)
+			if err != nil {
+				return nil, err
+			}
+			sortObservations(actual)
+			return actual, nil
 		})
 	}
 }
@@ -222,3 +233,21 @@ func simplifyNodes(results map[string][]*spanner.Edge) map[string][]*spanner.Edg
 	}
 	return filtered
 }
+
+// sortObservations sorts Observations by variable, entity, facet (primary key) to ensure deterministic order in tests.
+// The final Observation responses will be sorted later based on facet rank.
+func sortObservations(results []*spanner.Observation) {
+	sort.Slice(results, func(i, j int) bool {
+		a, b := results[i], results[j]
+
+		if a.VariableMeasured != b.VariableMeasured {
+			return a.VariableMeasured < b.VariableMeasured
+		}
+
+		if a.ObservationAbout != b.ObservationAbout {
+			return a.ObservationAbout < b.ObservationAbout
+		}
+
+		return a.FacetId < b.FacetId
+	})
+}

internal/server/spanner/query_builder.go

@@ -108,11 +108,7 @@ func GetNodeEdgesByIDQuery(ids []string, arc *v2.Arc, offset int32) *spanner.Sta
 	switch arc.Decorator {
 	case CHAIN:
 		prefix = statements.chainedEdgePrefix
-		if len(arc.Filter) > 0 {
-			returnEdges = statements.returnFilterChainedEdges
-		} else {
-			returnEdges = statements.returnChainedEdges
-		}
+		returnEdges = statements.returnChainedEdges
 	default:
 		prefix = statements.edgePrefix
 		if len(arc.Filter) > 0 {

internal/server/spanner/statements.go

@@ -49,8 +49,6 @@ var statements = struct {
 	returnChainedEdges string
 	// Subquery to return Edges with filters.
 	returnFilterEdges string
-	// Subquery to return Edges for arcs with chaining and filters.
-	returnFilterChainedEdges string
 	// Subquery to apply page offset.
 	applyOffset string
 	// Subquery to apply page limit.
@@ -135,8 +133,14 @@ var statements = struct {
 			value,
 			provenance`,
 	returnChainedEdges: `
-		RETURN
+		RETURN DISTINCT
 			m.subject_id,
+			n.subject_id AS value
+		NEXT MATCH (n)
+		WHERE
+		  n.subject_id = value
+		RETURN
+		  subject_id,
 			@result_predicate AS predicate,
 			'' AS provenance,
 			n.value,
@@ -168,24 +172,6 @@ var statements = struct {
 			predicate,
 			value,
 			provenance`,
-	returnFilterChainedEdges: `
-		RETURN
-			m.subject_id,
-			n.subject_id AS value
-		NEXT MATCH (n)
-		WHERE
-		  n.subject_id = value
-		RETURN
-		  subject_id,
-			@result_predicate AS predicate,
-			'' AS provenance,
-			n.value,
-			n.bytes,
-			n.name,
-			n.types
-		ORDER BY
-			subject_id,
-			value`,
 	applyOffset: `
 		OFFSET %d`,
 	applyLimit: fmt.Sprintf(`