Dealing with large ResultSets??

[Marcelo Epstein <ma...@epstein.com.br>]

Hi,
How can I get more than 1000 rows of a table.
I am using display tag and I really don´t want 1000+ Objects.
What is the best practice to do that?
Does ORM models like Hibernate, Ibatis and others can help me?

Thanks in advance.
Matiro.




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Re: Dealing with large ResultSets??

[Rick Reumann <st...@reumann.net>]

On Mon, Mar 29, 2004 at 09:25:07PM -0300, Marcelo Epstein wrote:

> How can I get more than 1000 rows of a table.
> I am using display tag and I really don´t want 1000+ Objects.
> What is the best practice to do that?
> Does ORM models like Hibernate, Ibatis and others can help me?
 
    I'm huge fan of iBATIS, but from my understanding none of
    the ORM models actually help here too much and actually can
    make things worse (more memory intensive). I find it best in
    a case where you need a pagation type of thing (ie
    google-like previous next buttons, etc) to roll your own
    solution with JDBC. For example say you want to have the
    user browse through thousands of person records but they
    need to be sorted by person's hair color (I know stupid
    example:). Now since you are sorting by hair color you
    really can't work with a new select each time such as WHERE
    emp_id > (last spot you left off at). Since your huge list
    is sorted by hair color, the only way I've found to do it is
    to build a pagation type of mechanism where you actually
    query for all the records but in your ResultSet loop you
    only build the objects you need and break from the loop when
    you have enough. It gets a bit tricky since you have to keep
    track of when to start building as well (keep track of the
    last count position you left at it). Your best bet is to
    probably use a disconnected RowSet. This way you don't have
    to requery the db each time and you don't have to hold your
    typical connected ResultSet connection open to the db. You
    could then build the new sets of objects from this RowSet.
    The drawback to this is if the data changes a lot between
    the user's attempts to do prev and next. Even with a new
    query each time to the db, if the data changes, things can
    get ugly, so I'd opt for using a disconnected RowSet.

    Others may have better suggestions.

-- 
Rick

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