It is true that the table obtains rows to calculate pagination data.
However, the getRowCount() method of TableDataProvider can be overridden
to return something other than 1 million rows. You can also override the
pagination text in the table header.
Typically, sorting and filtering are performed on all rows. However, if
you provide your own TableDataSorter and TableDataFilter classes, you
can have the database sort/filter data, instead.
Dan
matroska wrote:
>
> Hi,
>
> thank you for your good answer however i haven't understood if it is
> possible to obtain same features of non paginated table for what
> concerns filter criteria and sort criteria. Are they possible?
>
> Thanks in advance
> Tobia Loschiavo
>
>
> Brett Bergquist ha scritto:
>> matroska wrote:
>>> Hi,
>>>
>>> I have a very large db table ( 1 milion record) and I would like to
>>> paginate results not only with paginate control but calling many
>>> paginated db query to reduce memory and cpu overhead. I have found
>>> many tutorials on paginating large result with datatable but none
>>> using dataproviders. Is it possible? How can I achieve this?
>>>
>>> Thanks in advance
>>> Tobia Loschiavo
>>>
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>>>
>> It can be done but gets a little tricky. First, you cannot use the
>> pagination controls that are available with the table. The
>> underlying infrastructure requires that it knows the total rows and
>> may even iterate through all of them, so with a million rows, you
>> are right back where you started with consuming tremendous amounts of
>> memory and having terrible performance. The infrastructure really
>> needs redesign to not require that it have to be able to provide a
>> count or traverse all of the rows so that large tables can be
>> supported easier.
>>
>> What you can do is provide your own TableDataProvider. I use a class
>> derived from ObjectListDataProvider and fetch a page of records at a
>> time from the database, build the list and render. For paging, I use
>> the table footer facet and add my own paging controls that look like
>> the ones provided by the table. When fetching the records for the
>> page, I fetch an extra record to determine if there is another page
>> so that I can properly enable/disable the paging controls (next,
>> last, previous, first).
>>
>> If you are doing filtering and sorting you also have more issues. Of
>> course your fetching of the page of records needs to take into
>> consideration the filtering and sorting applied. Fortunately if the
>> TableDataProvider that you supply to the TableRowGroup is the same
>> instance as the TableDataSorter and TableDataFilter, then it is
>> assumed that your TableDataProvider will provide sorted and filtered
>> records. To integrate into the table nicely, you will need to
>> implement TableDataSorter and TableDataFilter in your
>> TableDataProvider class. You will need to keep track of the
>> TableDataSortCriteria and TableDataFilterCriteria that is applied by
>> the user through interacting with the table controls on the page and
>> use this criteria when retrieving your data for the page. One
>> wrinkle is that the code updates the TableDataSorterCriteria directly
>> without calling into the TableDataSort when the sort criteria is
>> changed from ascending to descending or vise-versa. Not good because
>> your custom TableDataSorter implementation has no idea that the
>> criteria has been changed.
>>
>> But in the end, it can be done. It is a lot of work and should be
>> much easier but if you really want to you can handle large tables.
>>
>>
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>> .
>>
>
>
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