Thanks. I see now the key difference. The queryWithRowHandler methods do not return anything! I was thinking the List was built anyway.
So, assuming I don't build my own List in the RowHandler, it saves memory. Got it. Definitely should be considered for larger result sets that only need to be processed once. Hugh On 1/31/08, Clinton Begin <[EMAIL PROTECTED]> wrote: > > Row handlers are not necessarily faster... they just use less memory. > Thus, if you count the time to resize arrays, grow the heap and possibly > garbage collect, they will be faster for indirect reasons. > > > > Internally, by default, iBATIS uses a RowHandler that simply gathers up > all of the result objects and adds them to a list to be returned (it > actually uses it even for a single queryForObject as well). > > > > So if you write your own RowHandler implementation, it's possible to > process row-by-row... > > > > That's a pretty rare thing to do in most transactional and/or web based > systems. It's more for batch processing of lots of rows. > > > > One example of where I used a row handler was for an integration task > between a MySQL database and a SQL Server... ETL of sorts. The RowHandler > would read from MySQL, transform the record, perform some simple > calculations, and batch inserts into SQL Server. On my test machine running > both databases (3GHz 2GB RAM 2x10k HDD), I was able to achieve throughput of > 15,000 records per second on millions of rows. > > > > So they CAN be fast. They aren't just fast by default, and they're not > for every situation. > > > > Clinton > > > > *From:* Hugh Ross [mailto:[EMAIL PROTECTED] > *Sent:* January-31-08 12:39 PM > *To:* user-java@ibatis.apache.org > *Subject:* How does RowHandler help performance? > > > > > > I've looked at the docs (In Action book, Developer Guide 2.0, and wiki), > and somehow I've missed this. > > > > I have seen threads in the user-java Mail Archive saying that it can, but > I'm not clear on how. > > > > Thanks... > > > > P.S. Actually, I believe only the Dev Guide mentions RowHandler > specifically, and there only briefly. >
