Update query_edge_limit config option info and error message. (#2979)

dgraph/cmd/alpha/run.go

@@ -153,7 +153,7 @@ 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.")
 
 	// TLS configurations
 	x.RegisterTLSFlags(flag)

query/query3_test.go

@@ -26,7 +26,6 @@ import (
 )
 
 func TestRecurseError(t *testing.T) {
-
 	query := `
 		{
 			me(func: uid(0x01)) @recurse(loop: true) {

query/recurse.go

@@ -136,8 +136,9 @@ func (start *SubGraph) expandRecurse(ctx context.Context, maxDepth uint64) error
 		}
 
 		if numEdges > x.Config.QueryEdgeLimit {
-			// If we've seen too many nodes, stop the query.
-			return ErrTooBig
+			// If we've seen too many edges, stop the query.
+			return x.Errorf("Exceeded query edge limit = %v. Found %v edges.",
+				x.Config.QueryEdgeLimit, numEdges)
 		}
 
 		if len(out) == 0 {

query/shortest.go

@@ -54,7 +54,6 @@ var pathPool = sync.Pool{
 }
 
 var ErrStop = x.Errorf("STOP")
-var ErrTooBig = x.Errorf("Query exceeded memory limit. Please modify the query")
 var ErrFacet = x.Errorf("Skip the edge")
 
 type priorityQueue []*Item
@@ -203,8 +202,9 @@ func (sg *SubGraph) expandOut(ctx context.Context,
 		}
 
 		if numEdges > x.Config.QueryEdgeLimit {
-			// If we've seen too many nodes, stop the query.
-			rch <- ErrTooBig
+			// If we've seen too many edges, stop the query.
+			rch <- x.Errorf("Exceeded query edge limit = %v. Found %v edges.",
+				x.Config.QueryEdgeLimit, numEdges)
 			return
 		}
 
@@ -315,9 +315,7 @@ func KShortestPath(ctx context.Context, sg *SubGraph) ([]*SubGraph, error) {
 				select {
 				case err = <-expandErr:
 					if err != nil {
-						if err == ErrTooBig {
-							return nil, err
-						} else if err == ErrStop {
+						if err == ErrStop {
 							stopExpansion = true
 						} else {
 							return nil, err
@@ -474,9 +472,7 @@ func ShortestPath(ctx context.Context, sg *SubGraph) ([]*SubGraph, error) {
 			select {
 			case err = <-expandErr:
 				if err != nil {
-					if err == ErrTooBig {
-						return nil, err
-					} else if err == ErrStop {
+					if err == ErrStop {
 						stopExpansion = true
 					} else {
 						return nil, err