Cannot open WAL database via web/wasm

[nmfisher]

Cannot open WAL database via web/wasm

[simolus3]

I have pushed a build without OMIT_WAL to https://storage.googleapis.com/simon-public-euw3/assets/sqlite3_with_wal.wasm. Ideally this should work by creating an IndexedDbFileSystem manually to create the three files if they don't exist.

We don't implement the shared memory parts of the VFS API though, and I'm not sure if they might be required. Unfortunately I don't have time to experiment with this today, but if you can't get it to work I can take another look. It might be that this will require more changes to the Dart bindings to work properly.

[simolus3]

The main reason we don't support WAL on the web is that it requires a shared-memory setup between different processes that share the shm file. We can't do that on the web at all, so we're also disabling WAL on the build to make the binary smaller.

We might be able to build a (unsound, but safe for read-only databases) sqlite3 module with WAL support, but some file system implementations (in particular, the ones using the file system API and OPFS) assume the default journal mode.
I can provide a wasm module without the OMITs, and then as long as you're using an IndexedDb or an in-memory database with WAL it should be fine.

[nmfisher]

Thanks for the quick response! A WAL build would be very useful, I'm only using IndexedDb so that's fine.

[nmfisher]

No problem, I'll have a tinker with that version. Thanks again for the help (and kudos for the great package).