I use this to get 10 "Article" items, ranked by "RankingDate":

DataObject::get("Article", $q ,'RankingDate DESC','','10');

I only want ODD items to be returned. Only the 1st, 3rd, 5th, 7th and 9th item should be returned.

The MySQL query for that looks something like this:

select *
from
(select *, @rn:=@rn+1 rn
from (select @rn:=0) r, `sitetree`
WHERE `ClassName` LIKE '%Article%'
order by `Title`
limit 10
) sq
where rn%2=1

How can I do this with DataObject::get()?

How about....

$dosArticle = DataObject::get("Article", '','RankingDate DESC','','20');
$dosOnlyOddArticle = new DataObjectSet();
if ($dosArticle)
	foreach($dosArticle as $doArticle)
	{
		if($doArticle->Odd())
		{
			$dosOnlyOddArticle->push($doArticle);
		}
	}
}

Thanks, swaiba. But your idea is not as kind on memory as if SQL did the work.

oh, it's didn't look like that would be an issue, but I guess you know where you need to optimise... I was always taught to get it working (whilst think of memory and CPU cycles) and then come back and address the demonstrated bottlenecks later...

why don't use directly query your datable using mysql_query or DB::query if this is a real memory hog that you want to streamline?