Avoiding introspection queries for built-in array types

[0xD09CD196D188D0B0]

Hi, and thanks for all the work on asyncpg! 👋

I’ve noticed that fresh connections usually emit introspection queries even for statements involving simple arrays of integers.

Looking at the code in init_array_codecs, asyncpg seems to initialize only the core codecs for _oid and _text (as mentioned in the comment, “to make type introspection query work”).

asyncpg/asyncpg/protocol/codecs/array.pyx

Lines 861 to 875 in 5b14653

	cdef init_array_codecs():
	# oid[] and text[] are registered as core codecs
	# to make type introspection query work
	#
	register_core_codec(_OIDOID,
	<encode_func>&arrayoid_encode,
	<decode_func>&arrayoid_decode,
	PG_FORMAT_BINARY)
	register_core_codec(_TEXTOID,
	<encode_func>&arraytext_encode,
	<decode_func>&arraytext_decode,
	PG_FORMAT_BINARY)
	init_array_codecs()

I was wondering: was there a particular reason that asyncpg doesn’t include more built-in types there? From my perspective, types like _int2, _int4, _int8, _float4, _float8, _bool, and _char are very commonly used in queries. Including them might avoid a lot of introspection queries on new connections.

Is this something that could be considered, or are there trade-offs I might be missing?