PaginatedList is meant for simple systems that have the luxury of keeping a page of data around in memory. In a high performance system that needs to scale, keeping even a page of records in memory is a bad idea...regardless of PaginatedList. Even 25 records per page could be devastating in a system with 10,000 concurrent sessions (in fact session management in general could be an issue at that point). So you're much better off just storing a) the current page and b) the page size --basically 2 that in total use up less memory than a single PaginatedList page...
PS: Doing a binary search is a) way slower and b) way more work than just doing count(1).
Cheers,
Clinton
On 6/28/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Hi Clinton,
I'm interested in knowing why you would discourage the use of the
paginated list in a "high performance" system?
In response to another post...
In order to compute the number of pages (using the paginatedlist), a
simple binary search method can be applied once when the result is first
queried. This binary search finds the last page in the set; reducing the
set by half on every iteration (hence binary). Of course, some critical
assumptions have to be made. The end result is something very similar to
google, where it tells you that your search yielded n pages with m
records... but when you click on the last page, those numbers are
re-adjusted. I hope this makes sense to you...
Nevertheless, I am more interested in why the use of the paginated list is
discouraged.
Thanks.
Aladin
> The documentation is mistaken. Previous() should not wrap for the
> paginated
> list. Regardless, you shouldn't use that approach to calculate the number
> of
> pages, you should use a separate count(*) query and divide by page size.
>
> For high performance systems, you should not use paginated list at
> all....you should use queryForList with skip and count parameters.
>
> Clinton
>
>
> On 6/27/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>>
>> Hello,
>>
>> I seem to be having some problem with the PaginatedList.
>>
>> When I'm on the first page and I do paginatedList.getPreviousPage(),
>> iBatis doesn't wrap to the last page... as specified in the javadoc. I
>> need this wrapping functionality to compute the total number of pages in
>> the result set.
>>
>> Does anyone have any idea as to why this might be happening?
>>
>> I am using postgres with jdb3.
>>
>> Thanks.
>> Aladin
>>
>
