documentation

shanty-data/src/mb_local.rs

@@ -44,20 +44,21 @@ impl LocalMusicBrainzFetcher {
     /// Check whether the database has been populated with data.
     pub fn is_available(&self) -> bool {
         let conn = self.conn.lock().unwrap();
-        // Check if the mb_artists table exists and has rows
+        // Check if the mb_artists table exists and has at least one row.
+        // Use EXISTS (SELECT 1 ...) instead of COUNT(*) to avoid scanning the entire table.
         conn.query_row(
-            "SELECT COUNT(*) FROM sqlite_master WHERE type='table' AND name='mb_artists'",
+            "SELECT EXISTS(SELECT 1 FROM sqlite_master WHERE type='table' AND name='mb_artists')",
             [],
-            |row| row.get::<_, i32>(0),
+            |row| row.get::<_, bool>(0),
         )
-        .map(|c| c > 0)
         .unwrap_or(false)
             && conn
-                .query_row("SELECT COUNT(*) FROM mb_artists LIMIT 1", [], |row| {
-                    row.get::<_, i32>(0)
-                })
-                .unwrap_or(0)
-                > 0
+                .query_row(
+                    "SELECT EXISTS(SELECT 1 FROM mb_artists LIMIT 1)",
+                    [],
+                    |row| row.get::<_, bool>(0),
+                )
+                .unwrap_or(false)
     }
 
     /// Get statistics about the imported data.