Improve SQLite performance (#2111)

* tune sqlite upon connection

* catch operational error

* use wal for journal_mode for faster performance

src/backend/base/langflow/services/database/service.py

@@ -9,6 +9,8 @@ from alembic.config import Config
 from loguru import logger
 from sqlalchemy import inspect
 from sqlalchemy.exc import OperationalError
+from sqlalchemy.engine import Engine
+from sqlalchemy import event
 from sqlmodel import Session, SQLModel, create_engine, select, text
 
 from langflow.services.base import Service
@@ -53,6 +55,20 @@ class DatabaseService(Service):
             max_overflow=self.settings_service.settings.max_overflow,
         )
 
+    @event.listens_for(Engine, "connect")
+    def on_connection(dbapi_connection, connection_record):
+        from sqlite3 import Connection as sqliteConnection
+
+        if isinstance(dbapi_connection, sqliteConnection):
+            logger.info("sqlite connect listener, setting pragmas")
+            cursor = dbapi_connection.cursor()
+            try:
+                cursor.execute("PRAGMA synchronous = NORMAL")
+                cursor.execute("PRAGMA journal_mode = WAL")
+                cursor.close()
+            except OperationalError as oe:
+                logger.warning("Failed to set PRAGMA: ", {oe})
+
     def __enter__(self):
         self._session = Session(self.engine)
         return self._session