DPL Example 027

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Optimum performance result scrolling for huge wikis

This page demonstrates how DPL can be used in really huge wikis like WIKIPEDIA to allow efficient scrolling through huge result sets. The approach ios very much straight forward:

  • We use count=50
  • When scrolling forward we use ascending order; when scrolling backward we internally use descending order but we reverse the result set for the user
  • Each query takes a lower or an upper limit for the search as a selection criterion; This criterion is set by an URL parameter which is deducted from information of the previous query: each query passes the first and last page of its result set to a scroll helper template.
  • The command scroll=yes is needed to enable scrolling.
  • The approach could be extended: The scroll helper could produce a set of fixed links for the initial letters; thus one could easily jump to A, B, C, ...
  • Note that the scroll helper optionally shows the %TOTALPAGES%. If you do not need the total count : leave it away. Then the SQL statement does not calculate the total size of the result set ("SQL_CALC_FOUND_ROWS"). Depending on your data and other selection criteria this may result in a small additional performance gain as you can see in the second example here.
  • The time spent within DPL is displayed at the bottom; usually it is below 30 msec.

Result with %TOTALPAGES%

Extension:DynamicPageList (DPL), version 3.2.1: Warning: No results.

Result without %TOTALPAGES%

Extension:DynamicPageList (DPL), version 3.2.1: Warning: No results.

| namespace          =
| category           = Events
| count              = {%DPL_count:50%}
| resultsheader      = ²{Extension DPL continue¦dir=%SCROLLDIR%¦pages=%PAGES%¦total=%TOTALPAGES%¦firsttitle=%FIRSTTITLE%¦lasttitle=%LASTTITLE%¦page={{FULLPAGENAME}}}²\n
| resultsfooter      = ²{Extension DPL continue¦dir=%SCROLLDIR%¦pages=%PAGES%¦total=%TOTALPAGES%¦firsttitle=%FIRSTTITLE%¦lasttitle=%LASTTITLE%¦page={{FULLPAGENAME}}}² %DPLTIME%\n
| scroll             = yes
| columns            = 3