JavaScript data grid for millions of rows
I need to present a large number of rows of data (ie. millions of rows) to the user in a grid using JavaScript.
The user shouldn't see pages or view only finite amounts of data at a time.
Rather, it should appear that all of the data are available.
Instead of downloading the data all at once, small chunks are downloaded as the user comes to them (ie. by scrolling through the grid).
The rows will not be edited through this front end, so read-only grids are acceptable.
What data grids, written in JavaScript, exist for this kind of seamless paging?
Answer
(Disclaimer: I am the author of SlickGrid)
UPDATE This has now been implemented in SlickGrid.
Please see http://github.com/mleibman/SlickGrid/issues#issue/22 for an ongoing discussion on making SlickGrid work with larger numbers of rows.
The problem is that SlickGrid does not virtualize the scrollbar itself - the scrollable area's height is set to the total height of all the rows. The rows are still being added and removed as the user is scrolling, but the scrolling itself is done by the browser. That allows it to be very fast yet smooth (onscroll events are notoriously slow). The caveat is that there are bugs/limits in the browsers' CSS engines that limit the potential height of an element. For IE, that happens to be 0x123456 or 1193046 pixels. For other browsers it is higher.
There is an experimental workaround in the "largenum-fix" branch that raises that limit significantly by populating the scrollable area with "pages" set to 1M pixels height and then using relative positioning within those pages. Since the height limit in the CSS engine seems to be different and significantly lower than in the actual layout engine, this gives us a much higher upper limit.
I am still looking for a way to get to unlimited number of rows without giving up the performance edge that SlickGrid currently holds over other implementations.
Rudiger, can you elaborate on how you solved this?