Accessing database from a background Isolate & main Isolate

[amugofjava]

Hi,

Firstly, thank you for your great packages. I've been using your Sembast for years and it has been rock solid and it's so easy to use. I am now looking to Sqlflite, as I thought you could use it to access a Sqlite database in the background, but I am unsure.

On the usage recommendation page and within some issues, it says that access should only occur in the main Isolate; however, on the changelog, v2.2.0+3 says initial support of cross Isolate safe.

Please could you clarify if accessing a database from both the main Isolate, and a background Isolate (e.g. for writing records during a scheduled task) is possible and/or recommended.

Apologies if I this is mentioned in a change or readme and I've missed it.

[alextekartik]

Indeed many people have asked about access from another isolate and unfortunately I don't have a good answer for that and the documentation is unclear about that, sorry.
It should work although I have not tested it much and I have avoided it (for example by saving the temporary data read
in a file that I handle later in the main isolate). One common usage
on Android and iOS is to have access from a push notification isolate or scheduled task.

• Good if you can avoid it and only limit to this case (background notification / scheduled task)
• In both isolates
  • Use singleInstance: false in openDatabase
  • Don't close the database
• Since hot reload might fail when using singleInstance: false (if done while a transaction is in progress), you
  can try singleInstance: true in the main isolate only.