sqldb: add UpsertSelfNode query

This query is less strict in terms of the latest update timestamp field.
We want to be less strict with our own node data since we always want
our own updates recorded.

sqldb/sqlc/queries/graph.sql

@@ -21,6 +21,27 @@ WHERE graph_nodes.last_update IS NULL
     OR EXCLUDED.last_update > graph_nodes.last_update
 RETURNING id;
 
+-- We use a separate upsert for our own node since we want to be less strict
+-- about the last_update field. For our own node, we always want to
+-- update the record even if the last_update is the same as what we have.
+-- name: UpsertSourceNode :one
+INSERT INTO graph_nodes (
+    version, pub_key, alias, last_update, color, signature
+) VALUES (
+    $1, $2, $3, $4, $5, $6
+)
+ON CONFLICT (pub_key, version)
+    -- Update the following fields if a conflict occurs on pub_key
+    -- and version.
+    DO UPDATE SET
+        alias = EXCLUDED.alias,
+        last_update = EXCLUDED.last_update,
+        color = EXCLUDED.color,
+        signature = EXCLUDED.signature
+WHERE graph_nodes.last_update IS NULL
+    OR EXCLUDED.last_update >= graph_nodes.last_update
+RETURNING id;
+
 -- name: GetNodesByIDs :many
 SELECT *
 FROM graph_nodes