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Class DSRG.MW.QueryEngine

java.lang.Object
   |
   +----DSRG.MW.QueryEngine

public class QueryEngine
extends Object

Variable Index

 o DEBUG
the debug flag
 o main
a handle to the Main class

Constructor Index

 o QueryEngine(Main)
the constructor takes the handle to the main class as argument.

Method Index

 o breakdown_query(View)
This method creates the queries that are sent to each IS.
 o computeExtent(View)
This method computes the extent of a view by using the queryBreakdown() method.
 o reassemble_query(String)
This method creates the reassembly query for the intermediate DB from which this view is computed.

Variables

 o main
 private Main main
a handle to the Main class

 o DEBUG
 private static final boolean DEBUG
the debug flag

Constructors

 o QueryEngine
 public QueryEngine(Main myMain)
the constructor takes the handle to the main class as argument. This is the only connection to the outside world that the query engine has

Methods

 o computeExtent
 public Table computeExtent(View v)
This method computes the extent of a view by using the queryBreakdown() method.

Returns:
Table for given View .
 o breakdown_query
 private Vector breakdown_query(View v)
This method creates the queries that are sent to each IS.
koeller 032999, we're replacing iterateClause with VKB-methods (View_Definition-Object).

Returns:
A Vector of ISQuery()'s.
 o reassemble_query
 public String reassemble_query(String viewName)
This method creates the reassembly query for the intermediate DB from which this view is computed.
Changed to use MKB objects instead of iterateClause, koeller 300399
we have a bug: the reassembly-query has where-clauses without the relation names. so if we have a join between attributes with the same name in relations with the same name, the query won't work

Returns:
A String with a SQL statement (standard SQL with SELECT/FROM/WHERE..)

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