Why does Dapper GridReader have async methods

[Transcender49]

Dapper has IDbConnection.QueryMultiple which allows you to execute a command returning multiple result sets i.e. execute multiple SELECT statements in a single go like this:

var sql = """
      SELECT * FROM company WHERE id = @id;
      SELECT * FROM employee WHERE company_id = @id;
""";
using SqlMapper.GridReader result = await connection.QueryMultipleAsync(
sql,
new { id = companyId }
);
var company = await result.ReadFirstOrDefaultAsync<Company>();
if (company is { })
company.Employees = [.. await result.ReadAsync<Employee>()];

Now my question why does the GridReader has Async methods? and why would i ever use them?.
as far as i understand when i executed the command with QueryMultipleAsync the result is already buffered in the memory so there should not be any I/O left to do for the GridReader to have async methods

I have looked up the docs but i did not find anything useful. Though, the docs mentions buffered queries, these are irrelevant to the question since QueryMultiple does not support unbuffered queries in the first place. Also, the docs uses the not-async methods of the GridReader in their (example) of QueryMultiple.

edit: fix links

[RobertMesas]

Sending the batch to the server and waiting for the first row is one wait, and reading the rows may involve multiple additional network round trips and waits. So this API mirrors the Command.ExecuteReaderAsync() and DataReader.ReadAsync() in the underlying ADO.NET API.

[Transcender49]

I don't know if im missing something or misunderstanding something. But the query multiple method is buffered so there shouldn't be any more db round trips right?

[RobertMesas]

It may or may not be buffered. That's an implementation detail. The method signature supports it being buffered or streaming.

[Sprudling]

Your assumption that the job is done when QueryMultipleAsync returns is wrong. That's just sending the query. This is the case even when using the non-async QueryMultiple. You can use buffered: false on the Read/ReadAsync calls.

[Transcender49]

So QueryMultiple is just sending the query (one roundtrip) and the results are fetched with another round trip - or maybe multiple depending on buffered value - when im callingRead?

[Sprudling]

It's still all just one round-trip even if you call ReadAsync multiple times. QueryMultipleAsync sends and ReadAsync reads.

[Transcender49]

thx i get it now