Transaction with Ecto multi

From the collection Ecto and Postgresql

1. Transactional Support: Ecto.Multi allows grouping multiple database operations into a single transaction. This ensures that either all operations succeed or none of them are persisted, maintaining data consistency.
2. Composition of Operations: You can compose different database operations such as inserts, updates, deletes, and queries in an organized and concise structure.
3. Parallel Execution: Operations within an Ecto.Multi can be executed in parallel, which can significantly improve performance in scenarios where multiple operations need to be performed simultaneously.

alias Ecto.Multi
multi = Multi.new()
|> Multi.insert(:user, User.changeset(%User{}, %{name: "Alice", age: 30}))
|> Multi.insert(:address, Address.changeset(%Address{}, %{street: "123 Main St", city: "Anytown"}))
case Repo.transaction(multi) do
{:ok, %{user: user, address: address}} ->
IO.puts "User and Address created successfully!"
{:error, _failed_op, _changeset, _multi} ->
IO.puts "Failed to create User or Address."
end

• Multi.new() creates a new transactional context.
• Multi.insert(:user, ...) and Multi.insert(:address, ...) are separate insert operations within the transaction.
• Repo.transaction(multi) executes all operations defined in multi within a single transaction. If all operations succeed, it returns {:ok, ...}, otherwise {:error, ...}.

• Atomicity: All operations within an Ecto.Multi are atomic, meaning either all are successfully performed, or none are persisted in the database.
• Flexibility: In addition to Multi.insert/3, there are functions such as Multi.update/4, Multi.delete/3, and Multi.run/4 that allow executing a wide range of operations within a single transaction.
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