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transaction(conn, fun, opts \\ [])

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transaction(conn(), (t() -> result), opts :: Keyword.t()) ::
  {:ok, result} | {:error, reason :: any()}
when result: var

Acquire a lock on a connection and run a series of requests inside a transaction. The result of the transaction fun is return inside an :ok tuple: {:ok, result}.

To use the locked connection call the request with the connection reference passed as the single argument to the fun. If the connection disconnects all future calls using that connection reference will fail.

run/3 and transaction/3 can be nested multiple times. If a transaction is rolled back or a nested transaction fun raises the transaction is marked as failed. All calls except run/3, transaction/3, rollback/2, close/3 and close!/3 will raise an exception inside a failed transaction until the outer transaction call returns. All transaction/3 calls will return {:error, :rollback} if the transaction failed or connection closed and rollback/2 is not called for that transaction/3.


  • :queue - Whether to block waiting in an internal queue for the connection's state (boolean, default: true). See "Queue config" in start_link/2 docs
  • :timeout - The maximum time that the caller is allowed to perform this operation (default: 15_000)
  • :deadline - If set, overrides :timeout option and specifies absolute monotonic time in milliseconds by which caller must perform operation. See System module documentation for more information on monotonic time (default: nil)
  • :log - A function to log information about begin, commit and rollback calls made as part of the transaction, either a 1-arity fun, {module, function, args} with DBConnection.LogEntry.t/0 prepended to args or nil. See DBConnection.LogEntry (default: nil)

The pool and connection module may support other options. All options are passed to handle_begin/2, handle_commit/2 and handle_rollback/2.


{:ok, res} = DBConnection.transaction(conn, fn conn ->
  DBConnection.execute!(conn, query, [])