> WITHOUT unidirectional I get a OUT OF MEMORY.
>
> WITH unidirectional I do not get this.

The unidirectional flag switch off to buffer rows in client.
You can't use Prev(), only Next().

If count of records is low, buffered dataset is good choice, you can
navigate inside this.
But if you need a lot of records in client, you need not buffered
(unidirectional). You can read all row forward, row by row, against eof.

eMeL

(sorry my terrible english)