How can I use savepoints with Ecto?

Questions / Help
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1

I’m looking to use savepoints to rollback within a larger transaction in case of an error, but didn’t see a way to start a “transaction” in Ecto in savepoint mode, as supported by the underlying postgrex (https://github.com/elixir-ecto/postgrex/blob/7ed8c3207a56a1f1ba886f2b1a935719999d4dd9/lib/postgrex.ex#L424).

Is there any way to do so using Ecto or would I need to work with Postgrex directly and manage connections separately?

2

Digging through the source, it appears that opts is threaded all the way from Ecto.Repo.transaction down to the underlying DB adapter, so passing savepoint: true to the public interface should do the right thing.

HOWEVER

The documentation for DBConnection.rollback specifically mention bubbling up to nested transactions; I suspect the code may be making assumptions that will make rolling back to a previous savepoint (without rolling back the enclosing transaction) tricky.

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