Add support for deleting non-existent UIDs in Upsert (#3412)

dgraph/cmd/alpha/upsert_test.go

@@ -693,6 +693,12 @@ upsert {
       uid(u2) <name> "user2" .
       uid(u1) <friend> uid(u2) .
     }
+
+    delete {
+      uid(u3) <friend> uid(u1) .
+      uid(u1) <friend> uid(u3) .
+      uid(u3) <name> * .
+    }
   }
 
   query {
@@ -703,6 +709,10 @@ upsert {
     user2(func: eq(email, "[email protected]")) {
       u2 as uid
     }
+
+    user3(func: eq(email, "[email protected]")) {
+      u3 as uid
+    }
   }
 }`
 	doUpsert := func(wg *sync.WaitGroup) {
@@ -755,3 +765,32 @@ upsert {
 }`
 	z.CompareJSON(t, expected, res)
 }
+
+func TestUpsertDeleteNonExistent(t *testing.T) {
+	require.NoError(t, dropAll())
+	require.NoError(t, alterSchema(`
+email: string @index(exact) @upsert .
+name: string @index(exact) @lang .
+friend: uid @reverse .`))
+
+	m := `
+upsert {
+  mutation {
+    delete {
+      uid (u1) <friend> uid ( u2 ) .
+    }
+  }
+
+  query {
+    user1(func: eq(name@en, "user1")) {
+      u1 as uid
+    }
+
+    user2(func: eq(name@en, "user2")) {
+      u2 as uid
+    }
+  }
+}`
+	_, _, _, err := mutationWithTs(m, "application/rdf", false, true, true, 0)
+	require.NoError(t, err)
+}

edgraph/server.go

@@ -524,8 +524,22 @@ func (s *Server) doMutate(ctx context.Context, mu *api.Mutation, authorize bool)
 			return s
 		}
 
+		// Remove the mutations from gmu.Del when no UID was found
+		gmuDel := make([]*api.NQuad, 0, len(gmu.Del))
+		for _, nq := range gmu.Del {
+			nq.Subject = getNewVal(nq.Subject)
+			nq.ObjectId = getNewVal(nq.ObjectId)
+
+			if !strings.HasPrefix(nq.Subject, "_:uid(") &&
+				!strings.HasPrefix(nq.ObjectId, "_:uid(") {
+
+				gmuDel = append(gmuDel, nq)
+			}
+		}
+		gmu.Del = gmuDel
+
 		// update the values in mutation block from the query block.
-		for _, nq := range append(gmu.Set, gmu.Del...) {
+		for _, nq := range gmu.Set {
 			nq.Subject = getNewVal(nq.Subject)
 			nq.ObjectId = getNewVal(nq.ObjectId)
 		}