Use WAL mode in SQLite bloblogs

yama/src/pile/local_sqlitebloblogs.rs

@@ -247,6 +247,13 @@ impl SqliteBloblogPile {
             )?;
         }
 
+        // Enable WAL mode for significantly better write performance.
+        connection.execute_batch(
+            "
+            PRAGMA journal_mode=WAL;
+        ",
+        )?;
+
         Ok(SqliteBloblogPile {
             inner: Arc::new(Mutex::new(Inner {
                 next_bloblog_id: 0,