Is it safe to delete sqlite's WAL file?

Question

I have a strange problem with Core Data in an iOS app where sometimes the WAL file becomes huge (~1GB). It appears there are other people with the problem (e.g. Cor

Answer 1

It baffles me how many people here are suggesting it's safe to delete WAL files, without even bad looks in their direction.

The documentation explicitly lists this as one of the official ways to corrupt a database. It doesn't say deleting a hot WAL may cause you to lose most recent transactions or something benign like that. It says it may corrupt the database.

Why? Because an application may have crashed in the middle of a checkpointing operation. When this happens, the database file itself is in an invalid state unless paired with the new data contained in the WAL.

So the answer is a clear no. Don't delete WAL files.

What you can do to clear the file is call PRAGMA schema.wal_checkpoint(TRUNCATE);