Use :prefix to query attached databases

[sbaildon]

SQLite allows attached databases, and their tables can be referenced by prefixing the schema name

ATTACH DATABASE "/tmp/database.db" AS another;
SELECT * FROM another.things; 

I think it makes sense to use ecto's :prefix option to query these schemas.

I'm currently using this patch like...

as = "another"

Repo.checkout(fn ->
    Repo.query("ATTACH DATABASE ? AS ?", ["/tmp/database.db", as])

    Repo.transact(fn ->
        {:ok, service} = Repo.insert(%Service{id: 1})
        Repo.insert(%Registry{id: 1, service_id: service.id}, prefix: as)
    end)

    Repo.query("DETACH DATABASE ?", [as])
end)

Where I'm wrapping a transaction with ATTACH/DETACH to insert rows with transactional guarantees across both databases

[warmwaffles]

I think prefix was for another_ for table names, not schemas. I'm unsure.

EDIT:
Nope I'm wrong https://elixirforum.com/t/ecto-schema-tables-for-multiple-schemas/55726/3

[warmwaffles]

Can you do me a favor as well and remove this

ecto_sqlite3/integration_test/test_helper.exs

Line 94 in 2f9a6ff

:prefix,

and let the integration tests run.

[warmwaffles]

We'll need to fix the assertions encountered with mix test

[sbaildon]

I need to understand why the attached database seemingly doesn't exist when running the ecto library tests, but I think we're close.

[warmwaffles]

Is this right? If someone has a prefix specified on the schema or relationship it should be put here.

[sbaildon]

Ah yes I think that's right

I tried this and got an error:

sqlite> attach ":memory:" as attached_db
sqlite> create table attached_db.things (thing string not null);
sqlite> create table attached_db.refs (thing_id bigint not null references attached_db.things(id));
Parse error: near ".": syntax error
  s (thing_id bigint not null references attached_db.things(id));
                                      error here ---^

but quoting the entire reference works:

sqlite> attach ":memory:" as attached_db
sqlite> create table attached_db.things (thing string not null);
sqlite> create table attached_db.refs (thing_id bigint not null references 'attached_db.things(id)');

[warmwaffles]

Take a look at how the posgres and mysql adapters do this. I want to try and stay as close to what they do. I haven't looked at it in a long time (like 2 years) and we probably need to make adjustments.