uk.ac.bbk.dcs.automed.qproc.reformulate
Class InverseRulesAlgorithm

java.lang.Object
  uk.ac.bbk.dcs.automed.qproc.reformulate.InverseRulesAlgorithm

public class InverseRulesAlgorithm
extends java.lang.Object

Implements Inverse Rules algorithm for LAV and BAV query processing as described in the following paper:-

           P.J. McBrien and A. Poulovassilis. P2P query reformulation over Both-as-View
           data transformation rules. In Proc of DBISP2P 2006.
 

Author:

Sandeep Mittal

Method Summary

static java.util.Map	invertRule(java.util.Map viewMap, int rangeSemantics) Takes a viewMap created by AtomicViewMap class and inverts the rules based on the map contents.
static java.util.Map	invertRule(ViewKey targetScheme, Cell rule, int rangeSemantics) Inverts a rule.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

invertRule

public static java.util.Map invertRule(java.util.Map viewMap,
                                       int rangeSemantics)
                                throws BuildViewException

Takes a viewMap created by AtomicViewMap class and inverts the rules based on the map contents.

Parameters:

viewMap - A transformation map created by AtomicViewMap class

rangeSemantics - RANGE_UPPER, RANGE_LOWER or RANGE_BOTH

Returns:

A Map of inverted rules with ViewKey as key and Cell tree as content.

Throws:

BuildViewException

invertRule

public static java.util.Map invertRule(ViewKey targetScheme,
                                       Cell rule,
                                       int rangeSemantics)
                                throws BuildViewException

Inverts a rule.

The definition of a construct c by a query of the form [h|Q] is inverted as follows:

• Replace each variable in Q that does not appear in h by a distinct Consti with arguments the variables in h.
• For each generator p<-cs in Q, generate a query defining cs in terms of [p|h<-c;Q'] where Q' contains all filters from Q.

Parameters:

targetSchemeInfo - SchemeInfo object for the target construct for which the transformation is defined.

rule - Transformation query specified for the sourceScheme

rangeSemantics - RANGE_UPPER, RANGE_LOWER or RANGE_BOTH

Returns:

HashMap containing ViewKey key and root cell of the new rule.

Throws:

BuildViewException