Allow the normalize limit to be changed via a flag. (#3490)

dgraph/cmd/alpha/run.go

@@ -155,7 +155,10 @@ they form a Raft group and provide synchronous replication.
 
 	flag.Uint64("query_edge_limit", 1e6,
 		"Limit for the maximum number of edges that can be returned in a query."+
-			" This is only useful for shortest path queries.")
+			" This applies to shortest path and recursive queries.")
+	flag.Uint64("normalize_node_limit", 1e4,
+		"Limit for the maximum number of nodes that can be returned in a query that uses the "+
+			"normalize directive.")
 
 	// TLS configurations
 	x.RegisterTLSFlags(flag)
@@ -472,6 +475,7 @@ func run() {
 	x.Config.DebugMode = Alpha.Conf.GetBool("debugmode")
 	x.Config.PortOffset = Alpha.Conf.GetInt("port_offset")
 	x.Config.QueryEdgeLimit = cast.ToUint64(Alpha.Conf.GetString("query_edge_limit"))
+	x.Config.NormalizeNodeLimit = cast.ToInt(Alpha.Conf.GetString("normalize_node_limit"))
 
 	x.PrintVersion()
 

query/outputnode.go

@@ -34,10 +34,6 @@ import (
 	"github.com/dgraph-io/dgraph/x"
 )
 
-const (
-	normalizeLimit = 10000
-)
-
 // ToJson converts the list of subgraph into a JSON response by calling toFastJSON.
 func ToJson(l *Latency, sgl []*SubGraph) ([]byte, error) {
 	sgr := &SubGraph{}
@@ -277,8 +273,8 @@ func merge(parent [][]*fastJsonNode, child [][]*fastJsonNode) ([][]*fastJsonNode
 	for _, pa := range parent {
 		for _, ca := range child {
 			cnt += len(pa) + len(ca)
-			if cnt > normalizeLimit {
-				return nil, x.Errorf("Couldn't evaluate @normalize directive - to many results")
+			if cnt > x.Config.NormalizeNodeLimit {
+				return nil, x.Errorf("Couldn't evaluate @normalize directive - too many results")
 			}
 			list := make([]*fastJsonNode, 0, len(pa)+len(ca))
 			list = append(list, pa...)

query/outputnode_test.go

@@ -26,6 +26,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/dgraph-io/dgraph/types"
+	"github.com/dgraph-io/dgraph/x"
 )
 
 func makeFastJsonNode() *fastJsonNode {
@@ -59,6 +60,9 @@ func TestEncodeMemory(t *testing.T) {
 }
 
 func TestNormalizeJSONLimit(t *testing.T) {
+	// Set default normalize limit.
+	x.Config.NormalizeNodeLimit = 1e4
+
 	if testing.Short() {
 		t.Skip("Skipping TestNormalizeJSONLimit")
 	}
@@ -92,6 +96,9 @@ func TestNormalizeJSONLimit(t *testing.T) {
 }
 
 func TestNormalizeJSONUid1(t *testing.T) {
+	// Set default normalize limit.
+	x.Config.NormalizeNodeLimit = 1e4
+
 	n := (&fastJsonNode{}).New("root")
 	require.NotNil(t, n)
 	child1 := n.New("child1")

x/config.go

@@ -20,6 +20,8 @@ type Options struct {
 	DebugMode      bool
 	PortOffset     int
 	QueryEdgeLimit uint64
+	// NormalizeNodeLimit is the maximum number of nodes allowed in a normalize query.
+	NormalizeNodeLimit int
 }
 
 var Config Options