graph: fix inefficient query for IsPublicNode

go.mod

@@ -213,6 +213,8 @@ replace github.com/gogo/protobuf => github.com/gogo/protobuf v1.3.2
 // allows us to specify that as an option.
 replace google.golang.org/protobuf => github.com/lightninglabs/protobuf-go-hex-display v1.33.0-hex-display
 
+replace github.com/lightningnetwork/lnd/sqldb => ./sqldb
+
 // If you change this please also update docs/INSTALL.md and GO_VERSION in
 // Makefile (then run `make lint` to see where else it needs to be updated as
 // well).

graph/db/graph_test.go

@@ -1593,6 +1593,8 @@ func TestGraphCacheTraversal(t *testing.T) {
 	require.Equal(t, numChannels*2*(numNodes-1), numNodeChans)
 }
 
+// fillTestGraph fills the graph with a given number of nodes and create a given
+// number of channels between each node.
 func fillTestGraph(t testing.TB, graph *ChannelGraph, numNodes,
 	numChannels int) (map[uint64]struct{}, []*models.Node) {
 
@@ -3995,6 +3997,25 @@ func TestNodeIsPublic(t *testing.T) {
 	)
 }
 
+// BenchmarkIsPublicNode measures the performance of IsPublicNode when checking
+// a large number of nodes.
+func BenchmarkIsPublicNode(b *testing.B) {
+	graph := MakeTestGraph(b)
+
+	// Create a graph with a reasonable number of nodes and channels.
+	numNodes := 8000
+	numChans := 4
+	_, nodes := fillTestGraph(b, graph, numNodes, numChans)
+
+	// Pick a random node to test.
+	nodePub := nodes[len(nodes)/2].PubKeyBytes
+
+	for b.Loop() {
+		_, err := graph.IsPublicNode(nodePub)
+		require.NoError(b, err)
+	}
+}
+
 // TestDisabledChannelIDs ensures that the disabled channels within the
 // disabledEdgePolicyBucket are managed properly and the list returned from
 // DisabledChannelIDs is correct.

sqldb/sqlc/queries/graph.sql

@@ -56,7 +56,7 @@ LIMIT $3;
 SELECT EXISTS (
     SELECT 1
     FROM graph_channels c
-    JOIN graph_nodes n ON n.id = c.node_id_1 OR n.id = c.node_id_2
+    JOIN graph_nodes n ON n.id = c.node_id_1
     -- NOTE: we hard-code the version here since the clauses
     -- here that determine if a node is public is specific
     -- to the V1 gossip protocol. In V1, a node is public
@@ -68,6 +68,13 @@ SELECT EXISTS (
     WHERE c.version = 1
       AND c.bitcoin_1_signature IS NOT NULL
       AND n.pub_key = $1
+    UNION ALL
+    SELECT 1
+    FROM graph_channels c
+    JOIN graph_nodes n ON n.id = c.node_id_2
+    WHERE c.version = 1
+      AND c.bitcoin_1_signature IS NOT NULL
+      AND n.pub_key = $1
 );
 
 -- name: DeleteUnconnectedNodes :many