8. All server paging

Large grid with 1,000,000,000 root cells and next unlimited child cells

• This example shows very large grid with million of root rows, thousand of columns and unlimited count of child rows.
  This example uses dummy page data Page.xml loaded for every page and child page.
  In real application you need to serve the pages data accordingly to show them in grid.
  
• As you can see, TreeGrid can display unlimited count of cells, here are displayed billions of cells.
  But, you must be able to serve such data from server side. Implementing server paging for such huge data is really not easy.
  You must use fast database and especially effective algorithm to fetch data for individual pages according to sort, filter, group and search settings, if you want to provide these features.
  And also provide the calculations, if you want to show some summary rows in grid.
  
• This example sets these attributes for paging, all for Cfg tag:

  • Paging

    ='3' for

    server root paging

    
    
    • PageLength='100' as expected count of rows at one page, if the page has not set Count attribute.
      
    • MaxPages='2' to have only few rendered pages at a time and clear the unused pages soon.
      

    • FastPages

      ='500' to merge unused empty pages to bigger units to not render too many html tags in grid.
      Bigger number speeds up grid rendering on start, but slightly slows down the rendering of individual pages.
      

    • PageLengthDiv

      ='50' divides the height of the FastPages by this number to decrease height of the grid body, because the most browsers have limits in tag heights.
      The usual value is to divide (the whole count of root rows + expanded children) / 50,000.
      

  • ChildPaging

    ='3' for

    server child paging

    
    
    • RemoveCollapsed='2' to clear the children when its parent becomes collapsed. It does not clear the data, only html display.

  • ChildParts

    ='2' for

    client paging of expanded children

    
    The client ChildParts with server ChildPaging provides server paging also for the expanded children.
    
    • ChildPartLength='100' specifies count of children in one child part.
      In this example it is set to maximum of the immediate children in one parent, so it renders (and also loads due ChildPaging='3') all children at once, but always on demand / scroll.
      
    • ChildPartMin='0' specifies count of children always rendered on start.
      Because of server child paging here, the children always need to be loaded first, so they cannot be rendered immediately.
      
    • MaxChildParts='4' to have only few rendered child parts at a time and clear the unused child parts soon.
      

  • ColPaging

    ='2' for

    client column paging

    
    Columns in TreeGrid can be paged only on client, the downloaded page must always contain data for all columns.
    
    • ColPageLength='10' specifies how many columns will be in one column page.
      The size of column page is usually slightly wider than grid area reserved for the variable columns.
      
    • ColPageMin='0' specifies how many columns will be always shown on the left.
      In this example no special column is on left, so minimal value is used to speed the grid up.
      
    • MaxColPages='2' to have only few rendered column pages at a time and clear the unused column pages soon.