Optimistic locking with Postgres in SQLx

[marvin-hsu]

I'm currently using SQLx in Rust to query Postgres, and I'm trying to implement optimistic locking. Typically, in Postgres, I would use xmin for this purpose. However, when attempting to execute the following query:

let row: (Uuid, i32) = sqlx::query_as("INSERT INTO example (name) VALUES ($1) RETURNING id, xmin")
    .bind("test")
    .fetch_one(&mut conn)
    .await
    .expect("Failed to insert row.");

I encounter a runtime error:

Failed to insert row.: ColumnDecode { index: "1", source: "mismatched types; Rust type `i32` (as SQL type `INT4`) is not compatible with SQL type `xid`" }

It seems that SQLx does not support this type directly. Does anyone have any ideas or suggestions on how to work around this issue?