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From Apache Wiki <wikidi...@apache.org>
Subject [Db-derby Wiki] Update of "OLAPRowNumber" by ThomasNielsen
Date Thu, 04 Oct 2007 11:17:28 GMT
Dear Wiki user,

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The following page has been changed by ThomasNielsen:
http://wiki.apache.org/db-derby/OLAPRowNumber

------------------------------------------------------------------------------
  == Proposed Changes ==
  ''DRAFT''
  
- Conceptually the steps needed are
+ The steps we propose taking are
   * The new syntax must be added to the SQL grammar 
-  * Each node in the query tree should be decorated with a {{{RowNumberNode()}}}
-  * A row number should be assigned to the Derby {{{ResultSet}}} after (during?) ordering/grouping.
+  * A {{{RowNumberColumnNode}}} is added to the querytree for every instance of {{{the ROW_NUMBER()}}}
in the query during compilation
+  * During code generation in {{{ResultColumnList.generateCore()}}} we trap instances of
{{{RowNumberColumnNode}}} in the querytree and generate code to virtually invoke {{{BaseActivation.getSetRowNumberValue()}}}
+  * During execution of the generated code {{{BaseActivation.getSetRowNumberValue()}}} handles
the incrementation and caching of rownumber values based for a given column.
+  * Optimization should cause the execution to stop once possible {{{WHERE}}} clauses are
satisfied.
  

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