Varlena Types

src/postgres/third-party-extensions/pgrx/docs/src/pg-internal/varlena.md

2026.1.1.0-b16307 B

Conceptually, any "varlena" type is:

rust

#[repr(C, packed)]
union varlena {
    packed: (u8, [u8]),
    full: (u32, [u8]),
}

Unfortunately, Rust does not take kindly to ?Sized unions, and it would be a bit dodgy in C, too.