Opening a sqlite3 DB on a read-only filesystem with a -journal file

Question

I've got a sqlite3 DB that I need to read (not write) sitting on a read-only filesystem. There is also a -journal file associated with the database, which is interfering with opening the database because the first thing the sqlite code wants to do is delete that -journal file and it cannot because the filesystem is read-only. Setting the journal_mode to off doesn't help because that apparently only applies to new transactions. Is there a way to tell sqlite3 to simply ignore all mention of a -journal file associated with a DB?

Answer 1

Unfortunately no.

The problem is that the existence of a journal file indicates that a transaction was left in an incomplete state, and needs to be rolled back by transferring the content of the journal file back into the database file.

This requires write access to the file system, and SQLite will not allow you to open the file without performing this rollback.

You can read more about this here: Read-Only Databases:

No SQLite database (regardless of whether or not it is WAL mode) is readable if it is located on read-only media and it requires recovery. So, for example, if an application crashes and leaves an SQLite database with a hot journal, that database cannot be opened unless the opening process has write privilege on the database file, the directory containing the database file, and the hot journal. This is because the incomplete transaction left over from the crash must be rolled back prior to reading the database and that rollback cannot occur without write permission on all files and the directory containing them.

If you don't care about the possible corruption that discarding the journal file might lead to, you can make a copy of the database file, and leave the journal behind. Though, if you have the ability to do that, I would in fact copy the journal file too, to a writable file system, and open that database as normal, which would roll back the transaction properly.

The copy on the read-only file system though is not usable in its current state.