> Aight, I'll bite: continue or stop... and do what? As others have pointed out, the only safe option to get back to a consistent state is to roll back to a safe point.

Attempt to recover! Again, not all checksum errors are impossible to recover. I hold the view that even if there is a 1% chance of recovery, we should attempt it. This may be done by SQLite, an external tool, or even manually. Since WAL corruption issues are silent, we cannot do that now.

There is a smoll demo in the post. In it, I corrupt an old frame that is not needed by the database at all. Now, one approach would be to continue the recovery and then present both states: one where the WAL is dropped, and another showing whatever we have recovered. If I had such an option, I would almost always pick the latter.

>I corrupt an old frame that is not needed by the database at all

1. How does the database know that.

2. In your example Alice gets the money from nowhere. What if another user had sent the money to Alice and that frame get corrupted. Then you just created 10,000,000 from nowhere.

At the very least, rolling back to a good point gives you an exact moment of time where transactions can be applied from. Your example is very contrived and in a database where several transactions can be happening, doing a partial recovery will destroy the consistency of the database.

The demo is good, through I wish you had presented it as text rather than as a gif.

I do see your point of wanting an option to refuse to delete the wal so a developer can investigate the wal and manually recover... But the the typical user probably wants the database to come back up with a consistent, valid state if power is lost. They do not want have the database refuse to operate because it found uncommitted transactions in a scratchpad file...

As a SQL-first developer, I don't pick apart write-ahead logs trying to save a few bytes from the great hard drive in the sky, I just want the database to give me the current state of my data and never be in an invalid state.

What about all classes of durability errors that do not manifest in corrupted checksums (e.g. "cleanly" lost appends of entire transactions to the WAL)?

It seems like you're focusing on a very specific failure mode here.

Also, what if the data corruption error happens during the write to the actual database file (i.e. at WAL checkpointing time)? That's still 50% of all your writes, and there's no checksum there!

> Since WAL corruption issues are silent, we cannot do that now.

You do have backups, right?