Query.executeAndFetchFirst should not read all results about sql2o HOT 6 CLOSED

Anyone have thoughts on this? I have the code ready to rock and will send a pull request soon

from sql2o.

I agree that sql2o really needs a way to lazy-fetch from the database with a cursor while the connection is open, but I have never concluded how best to implement it.
I'm really curious how you solved it! How do you make curtain that the connection is closed after use?

from sql2o.

Well, you cannot make certain that the connection is closed after use, because exposing an iterable means you have no idea when someone will stop iterating. You cannot simply close the connection when iterating completes, because someone might only pull out 1000 results then decide to stop iterating. I believe the best you can do is make it easy to figure out for a developer that wants to use lazy functionality.

You can see what I did here: https://github.com/aldenquimby/sql2o/blob/master/src/main/java/org/sql2o/Query.java#L274

You can see Java 6 usage by looking at the executeAndFetch method in the link above.

Basic Java 7 usage would look like this:

try (ResultSetIterable<MyClass> rsIterable = query.executeAndFetchLazy(MyClass.class))
{
    for (MyClass obj : rsIterable)
    {
        // do work here, maybe flush 1000 results at a time or something
    }
}

from sql2o.

Wow, that is a way better solution that I had in mind. This is indeed a very valuable addition to the project! If you create a pull request, I will happily merge it in, and release a new version soon.

from sql2o.

Ok great! I will add a few more tests before submitting a pull request. Also I would like to move ResultSetIterator to another file (so that it isn't a subclass of Query), but then I wouldn't have access to the method getRSVal.

Could I move this to some sort of utility class? Or do you think I should just leave the iterator as an inner class of query?

from sql2o.

You could perhaps change the accessibility of the getRSVal method to be package internal, and move the ResultSetIterator to a new class in the same package.

Alternatively the getRSVal method could be moved to a utility class in the tools package and made public.

Either way, I think it is best to get it out of Query

from sql2o.