hide large number of rows, performance

[Giancarlo Aguilera]

Hello All!

I''m facing an issue trying to hide a large number of rows in a gridcontrol (3.3.0.11), I''m talking about at least a 1000 rows. I''m following the beginupdate/endupdate pattern; however, it takes a very long time. I''ve used both hiderows and setrowhidden. Any suggestions or is this an issue?

Many thanks

GA

[Administrator]

If you need to hide large numbers of rows, then doing it dynamically at runtime is the more efficient.

One way you can do this is to handle the grid.model.QueryRowHeight event. There, if e.index points to a row you want hidden, set e.Size = 0 and e.handled = true.

[Leow Kah Man]

Why is HideRows so slow?

The grid turns to blank, in the process.
Long enough to be noticeable.

[Administrator]

Hi Leow,

The Rows.Hidden is actually a dictionary. When you hide a row, an entry is created in the dictionary, and when you make a row visible, this entry is removed from the dictionary. When you call Hidden.SetRange, the grid will only allocate storage for the entries that you specify. This means that if you have 5,000,000, and hide every other one with this technique, then there will be 2.5M entries. However, in such a situation, you could implement such a grid virtually using QueryRowHeight with no memory allocationn. I guess my commnet was to suggest if you use a virtual grid, special knowledge of what you are trying to hide may allow you to do something more economical than the standard implementation that has to work for any case.

Another consideration for the short term is that grids with a large number of hidden rows can have poor scrolling performannce. If you manage your own dictionary, you can actually avoid this scrolling performance penalty by treating all rows as if they were contiguous no matter where they are in your external data source. This would mean that you would have row map allocated, but it would enhanced scrolling performance for the time being.

Thanks,
Haneef

[Leow Kah Man]

If the rowheight is 0, for rowindex 2,3,4.
If I am now at 5, and trying to use the arrow keys to move up to 1, will i have to press 4 times?

[Leow Kah Man]

I created a small sample to test and find that it works beautifully.

Thank you.

[Administrator]

Hi Leow,

You will be able to navigate to the Previous/next row in the grid as usual, even though the rows in between may be hidden. This should be fine.

Thanks,
Rajagopal

[Bryan Roberts]

I am having a similar issue, but when I change the height to 0 it actually takes longer then HideRows() with a large number of rows (greater than 30k). Any suggestions?

Thanks in advance,

Bryan

[Arun Kumar V]

Hi Bryan,

Thanks for your interest in Syncfusion products.

Query: Performance Issue : HideRows() with a large number of rows.

The problem is that the you may have used the implementation of HiddenRows.SetRanges(). It will visit every row  in the range and set all style property . This will take time for large number of rows. To improve the performance by using the .RowHeights.SetRange and ResetRanges method. <code> grid.RowHeights.SetRange(0, INITIAL_ROW_COUNT,ihidden_row,true); grid.RowHeights.ResetRange(0, INITIAL_ROW_COUNT); </code>

Please let me know if you have any other concerns.

Regards,

Arun

[Bryan Roberts]

Do you make the reset range right after the SetHeights call? Also what is the third variable being passed in SetHeights()?

-Bryan

[Arun Kumar V]

Hi Bryan,

Thanks for the update.

Query: Explanation regarding third variable being passed in SetHeights()?

The third argument variable will get the sizes to be applies to the range. Regarding reset range we have already provided sample in the below forum link.  It seems you have posted the same query in an another forum and we have updated solution regarding that. http://www.syncfusion.com/support/forums/grid-windows/106437 Please follow up that forum­ (106437) for further updates.

Regards,

Arun.