`opentelemetry-instrumentation-asyncpg`: allow opting out of instrumentation for async cursors

[krishnan-chandra]

What problem do you want to solve?

Currently, the AsyncPGInstrumentor instruments these async methods, including CursorIterator.__anext__.

In conjunction with this, it means that a span is fired for every single row that is iterated over from an async cursor. This causes certain traces to become unsustainably large and contain a massive number of spans like the one below:

Describe the solution you'd like

Allow opting out of instrumentation for CursorIterator.__anext__, or implement instrumentation at the network request level so that every fetch to the database triggers a span rather than every single row that is iterated over.

Describe alternatives you've considered

No response

Additional Context

No response

Would you like to implement a fix?

None

[alexmojaki]

Long-lived versions of the code links:

opentelemetry-python-contrib/instrumentation/opentelemetry-instrumentation-asyncpg/src/opentelemetry/instrumentation/asyncpg/__init__.py

Lines 129 to 137 in 38f0e33

	for method in [
	"Cursor.fetch",
	"Cursor.forward",
	"Cursor.fetchrow",
	"CursorIterator.__anext__",
	]:
	wrapt.wrap_function_wrapper(
	"asyncpg.cursor", method, self._do_cursor_execute
	)

opentelemetry-python-contrib/instrumentation/opentelemetry-instrumentation-asyncpg/src/opentelemetry/instrumentation/asyncpg/__init__.py

Line 186 in 38f0e33

"""Wrap cursor based functions. For every call this will generate a new span."""