There are already "first" and "rows" attributes for dataTable that match your "start" and "number of rows to display" parameters.
It's probably just a matter of providing a backing data model that lazy-loads the data. The view layer can (and does) provide an API for specifying what data to load, but your business /backing layer has to provide the mechanism for loading the data. On 9/8/05, David Haynes <[EMAIL PROTECTED]> wrote: > Kevin and Mike: > This comes back to the issue I was raising earlier this week regarding > parameterized dataTables. There are a number of cases where it would be > nice to be able to set some values for use by the backing bean when it > is invoked by the dataTable tag. In this case, being able to specify a > 'start' and 'number of rows' value would make the ResultSet more manageable. > > It seems to me that the current dataTable tag has the assumption that > the backing bean will hand it a complete result set and that is what is > to be displayed. This is OK as far as it goes (and from a pure object > perspective, makes sense) but there seems to be a disconnect between the > handling of large result sets and this model. The disconnect comes from > our desire not to consume so much system resource. The fact that there > is no way to limit the size of the result set other than in a static > manner - that is, the limits to the result sets are hard-coded in the > backing bean - severely restricts how dataTable may be used. > > At a minimum, it would be nice to have parameters for start and number > of rows that could be set for the dataTable. In a larger sense, it would > be nice to be able to specify any set of name/value pairs that the > backing bean could then use as it saw fit. You could even have a new > dataTable type, say dynamicDataTable, to address this if it made more sense. > > -david- > > Kevin Galligan wrote: > > > "...value binding for the whole set of data". 10,000 rows, at a > > maximum, or literally millions of rows? I guess I don't understand > > what you're really looking for. If you want to keep the results in > > session, yeah, they're in memory. Not millions of rows. Just > > whatever your search results are. If you don't want to keep them in > > memory you can try using the resultset datamodel implementation, which > > I assume is not ripping through the whole result set and building a > > version in memory or anything. > > > > I don't know how resultset keeps its data. I probably should figure > > that out considering my chosen profession. > > > > If you're going to be working with huge results to link to data, this > > might not be your best method. At results of that size, if this will > > be a well traveled system, you might want to use something a little > > more low level and link that into your faces code. > > > > However, 10,000 row result reports is begging for a different design, > > IMHO. > > > > Dave wrote: > > > >> Normally we have filters to select a portion of data from database > >> table. But it can be very large too. For example, searching found > >> 10,000 items. For the backend, ResultSet will have the 10,000 > >> records. I am trying to understand how the ResultSet manages the > >> 10,000 records. It would consume lots of memory if all of them in > >> memory. For dataTable scroller, I still need to provide value binding > >> for the whole set of data. > >> > >> */Kevin Galligan <[EMAIL PROTECTED]>/* wrote: > >> > >> Out of curiosity, how are you planning to use the millions of > >> rows? I > >> would assume you'd want to filter them in some way rather than > >> attempt > >> to display them, right? That would kind of answer your question > >> (your > >> datatable would only have the filtered results. Not the full table). > >> > >> Mike Kienenberger wrote: > >> > Data fetching would depend on your backing Collection. > >> > > >> > You can use t:dataScroller to limit the dataTable to accessing > >> only a > >> > subset of the data. > >> > > >> > I'd love to see a t:liveGridDataTable component like what's > >> available > >> > at this site, but I suspect it's currently outside of my > >> ability to > >> > implement. > >> > > >> > http://openrico.org/rico/livegrid.page > >> > > >> > On 9/8/05, Dave wrote: > >> > > >> >>For a large database table that has millions of records(rows), > >> how is the > >> >>memory managed from backend to ? all the millions of records > >> >>are in memory? That would crash the system. Is the collection( > >> returned from > >> >>database layer) actually not filled with data until they are > >> requested ? > >> >>Thanks. Dave > >> >> > >> >>__________________________________________________ > >> >>Do You Yahoo!? > >> >>Tired of spam? Yahoo! Mail has the best spam protection around > >> >>http://mail.yahoo.com > >> > >> ------------------------------------------------------------------------ > >> Click here to donate to the Hurricane Katrina relief effort. > >> <http://store.yahoo.com/redcross-donate3/> > > > > > > > > >
