SQLite state file may be partially written after interrupted Reflex 0.5.0 migration

Question

When upgrading a Reflex application from a version that used in‑memory state to Reflex 0.5.0, the framework expects a SQLite database at the location previously used for state storage. The supplied reflex migrate-state command copies the existing in‑memory state into this new file, but the operation is not wrapped in a transaction. If the migration is halted—by a power loss, process kill, or user interruption—the SQLite file can be left partially written or corrupted. On the next start, Reflex treats this as a fatal error and fails to launch, with no automatic rollback to the previous in‑memory state.
What mechanisms, if any, does Reflex provide to detect a partially written SQLite state file after an interrupted migration?
Should users rely solely on pre‑migration backups and integrity checks, or is there a preferred automated fallback strategy?
Is there a plan to make the migration command transactional or to introduce an automatic rollback mechanism in a future release?

Tasadduq Burney · Answer

Answer
Reflex does not add its own detection or automatic rollback for a partially written SQLite state file. You must rely on SQLite’s built‑in atomicity guarantees and run a manual integrity check after an interruption.
Likely explanation
The reflex migrate-state command copies in‑memory state into a new SQLite file without wrapping the copy in an explicit transaction. If the process is killed before the copy finishes, SQLite’s journaling (rollback journal or WAL) may contain uncommitted changes, but the main database file usually remains unchanged until a commit occurs. On the next open SQLite will roll back any incomplete transaction unless the journal files are missing or damaged.
Confirmed facts

SQLite guarantees atomicity via its journaling modes; after a crash, PRAGMA integrity_check; will report any structural corruption.
If the integrity check passes, the database is usable and any incomplete transaction has been rolled back automatically.
Presence of -journal, -wal, or -shm files indicates an interrupted transaction that SQLite will handle on next open.

Steps to verify and recover

Locate the SQLite state file (e.g., state.sqlite) and any companion files (state.sqlite-journal, state.sqlite-wal, state.sqlite-shm).
Open a shell and run the SQLite CLI:
sqlite3 state.sqlite "PRAGMA integrity_check;"

If the output is ok, the database is structurally sound and can be used; you may safely delete the journal/WAL files if they persist.
If the integrity check reports errors, restore the state file from a pre‑migration backup, or delete the corrupted journal/WAL files and re‑run reflex migrate-state.
Optionally, verify readability with a simple query:
sqlite3 state.sqlite "SELECT 1;"

Fallback strategy
There is no automated fallback inside Reflex. The recommended practice is to keep a backup of the pre‑migration state file (or the in‑memory state snapshot) and rely on the integrity check described above. If the check fails, restore from backup and retry the migration.
Future plans
As of Reflex 0.5.0, the migration command is not transactional and there is no announced plan to add automatic rollback. Users should monitor the project’s release notes for any changes that make the migration atomic.

SQLite state file may be partially written after interrupted Reflex 0.5.0 migration

1 answer

Answer

Likely explanation

Confirmed facts

Steps to verify and recover

Fallback strategy

Future plans

Your perspective belongs here.

0 question comments