Update app.py

app.py

@@ -87,25 +87,32 @@ class ModelDatabase:
             # Ensure the file exists before trying to connect
             if not os.path.exists(db_path):
                  raise FileNotFoundError(f"Database file not found at {db_path}")
-            disk_conn = sqlite3.connect(f'file:{db_path}?mode=ro', uri=True, check_same_thread=False, timeout=120) # Increased timeout
-            print("Applying PRAGMAs to source connection for backup performance...")
-            disk_conn.execute("PRAGMA journal_mode = OFF")
+            # Use a longer timeout just in case connection takes time, e.g. on network drives
+            disk_conn = sqlite3.connect(f'file:{db_path}?mode=ro', uri=True, check_same_thread=False, timeout=120)
+
+            # --- Adjusted PRAGMAs for disk_conn (read-only source) ---
+            # Apply PRAGMAs that are safe for read-only and might speed up the backup read
+            print("Applying safe PRAGMAs to source connection for potentially faster read...")
+            # synchronous=OFF is generally safe for read-only access
             disk_conn.execute("PRAGMA synchronous = OFF")
-            # Use a larger cache for reading from disk, e.g., 2GB = -2097152 KiB
-            disk_conn.execute("PRAGMA cache_size = -2097152")
+            # Set a large cache size to potentially speed up reading from disk during backup
+            disk_conn.execute("PRAGMA cache_size = -2097152") # ~2GB cache, adjust if needed
+            # temp_store=MEMORY is safe and might help if temporary tables are used internally
             disk_conn.execute("PRAGMA temp_store = MEMORY")
-            disk_conn.execute("PRAGMA locking_mode = EXCLUSIVE") # Prevent interference during backup
+            # Removed PRAGMA journal_mode = OFF as it caused the disk I/O error
+            # Removed PRAGMA locking_mode = EXCLUSIVE as it's not needed for read-only source
+            print("Read-safe PRAGMAs applied to source connection.")
+            # --- End of Adjusted PRAGMAs ---
+
 
             # 2. Connect to the target in-memory database
             print("Creating in-memory database...")
-            # Increase timeout for potential long operations on the in-memory DB too
             self.conn = sqlite3.connect(':memory:', check_same_thread=False, timeout=120)
-            self.conn.row_factory = sqlite3.Row # Use Row factory for dict-like access
+            self.conn.row_factory = sqlite3.Row
 
             # 3. Backup data from disk to memory
             print("Starting database backup from disk to memory (this may take a while)...")
             start_backup = time.time()
-            # Use a context manager for the destination connection to handle commits/rollbacks
             with self.conn:
                 disk_conn.backup(self.conn)
             end_backup = time.time()
@@ -113,35 +120,30 @@ class ModelDatabase:
 
             # 4. Apply PRAGMAs suitable for the in-memory database
             print("Applying PRAGMAs to in-memory database...")
-            # temp_store=MEMORY is default for :memory:, but explicit is fine
             self.conn.execute("PRAGMA temp_store = MEMORY")
-            # cache_size might still help slightly, but OS caching is dominant. Can be omitted.
-            # self.conn.execute("PRAGMA cache_size = -4194304") # e.g., 4GB cache within RAM
+            # Optional: Set cache size for in-memory DB if desired, though less critical
+            # self.conn.execute("PRAGMA cache_size = -4194304") # e.g., 4GB
 
             # 5. Ensure indices exist on the in-memory database *after* data loading
             print("Creating indices on in-memory database...")
             start_index = time.time()
-            self._ensure_indices() # This now operates on self.conn (the memory DB)
+            self._ensure_indices() # Operates on self.conn (memory DB)
             end_index = time.time()
             print(f"Index creation completed in {end_index - start_index:.2f} seconds.")
 
         except sqlite3.Error as e:
             print(f"SQLite error during database initialization: {e}")
-            if self.conn:
-                self.conn.close()
-                self.conn = None
-            raise # Re-raise the exception to signal failure
+            if self.conn: self.conn.close(); self.conn = None
+            raise # Re-raise to signal failure
         except FileNotFoundError as e:
              print(f"Error: {e}")
              raise
         except Exception as e:
             print(f"Unexpected error during database initialization: {e}")
-            if self.conn:
-                self.conn.close()
-                self.conn = None
+            if self.conn: self.conn.close(); self.conn = None
             raise
         finally:
-            # 6. Close the disk connection, it's no longer needed
+            # 6. Close the disk connection
             if disk_conn:
                 disk_conn.close()
                 print("Closed connection to disk database.")
@@ -149,6 +151,7 @@ class ModelDatabase:
         if self.conn:
              print("In-memory database initialized successfully.")
         else:
+             # This path should ideally not be reached if exceptions are raised properly
              print("Error: In-memory database connection failed.")
              raise RuntimeError("Failed to establish in-memory database connection.")