Streaming read result

[tisonkun]

I have found these related issues/pull requests

Currently, all the query* methods take local reference and thus even if we build a Stream with fetch, it must be collected in place, rather than be possible to return from the function.

Description

As above. To support streaming read result later, the lifetime bound shoudl be relaxed, e.g., accepting String.

Prefered solution

As described above.

Is this a breaking change? Why or why not?

I don't know.

[iamjpotts]

@tisonkun what driver(s) were you using when you ran into this?

MySql or sqlite? Postgres? the Any driver?

[tisonkun]

@iamjpotts I mainly use Postgres

[iamjpotts]

Do you have an example that does not compile?

Something similar to this should compile; this binds a reference and returns a Stream of rows:

fn get_interesting_rows<'a>(
    row_ids: impl AsRef<[Uuid]> + 'a,
    ex: impl sqlx::PgExecutor<'a> + 'a,
) -> impl Stream<Item = sqlx::Result<InterestingRow>> + 'a {
    let row_ids = row_ids.as_ref();

    sqlx::query!(
        r#"
            select
                row_id,
                row_value
            from interesting
            where
                row_id = any($1)
        "#,
        row_ids
    )
    .fetch(ex)
}

Notice that this constrains the lifetime of the references to be the same as the lifetime of the returned stream; however it does accomplish your goal of using a function to build the query and return an owned row stream.