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From rve...@apache.org
Subject [14/50] [abbrv] jena git commit: JENA-800 : Reorder function corresponding to that in 2.11.2.
Date Mon, 10 Nov 2014 10:53:19 GMT
JENA-800 : Reorder function corresponding to that in 2.11.2.

Project: http://git-wip-us.apache.org/repos/asf/jena/repo
Commit: http://git-wip-us.apache.org/repos/asf/jena/commit/a9c7671c
Tree: http://git-wip-us.apache.org/repos/asf/jena/tree/a9c7671c
Diff: http://git-wip-us.apache.org/repos/asf/jena/diff/a9c7671c

Branch: refs/heads/JENA-507
Commit: a9c7671cdd2b6d7c8c9c2031aac41b325cac91e1
Parents: ef40d6b
Author: Andy Seaborne <andy@apache.org>
Authored: Wed Nov 5 11:26:46 2014 +0000
Committer: Andy Seaborne <andy@apache.org>
Committed: Wed Nov 5 11:26:46 2014 +0000

----------------------------------------------------------------------
 .../optimizer/reorder/ReorderFixedAlt.java      | 80 ++++++++++++++++++++
 1 file changed, 80 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/jena/blob/a9c7671c/jena-arq/src/main/java/com/hp/hpl/jena/sparql/engine/optimizer/reorder/ReorderFixedAlt.java
----------------------------------------------------------------------
diff --git a/jena-arq/src/main/java/com/hp/hpl/jena/sparql/engine/optimizer/reorder/ReorderFixedAlt.java
b/jena-arq/src/main/java/com/hp/hpl/jena/sparql/engine/optimizer/reorder/ReorderFixedAlt.java
new file mode 100644
index 0000000..e5014c9
--- /dev/null
+++ b/jena-arq/src/main/java/com/hp/hpl/jena/sparql/engine/optimizer/reorder/ReorderFixedAlt.java
@@ -0,0 +1,80 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hp.hpl.jena.sparql.engine.optimizer.reorder;
+
+import static com.hp.hpl.jena.sparql.engine.optimizer.reorder.PatternElements.TERM ;
+import static com.hp.hpl.jena.sparql.engine.optimizer.reorder.PatternElements.VAR ;
+
+import com.hp.hpl.jena.sparql.engine.optimizer.Pattern ;
+import com.hp.hpl.jena.sparql.engine.optimizer.StatsMatcher ;
+import com.hp.hpl.jena.sparql.graph.NodeConst ;
+import com.hp.hpl.jena.sparql.sse.Item ;
+
+/**
+ * Alternative fixed reorder function. This corresponds to the algorithm prior
+ * to Jena 2.11.2. It is susceptable to picking bad orders when there are lots
+ * of non-characterstic (non-selective) rdf:type triples.
+ * <p>
+ * The default "ReorderFixed" is better in most cases because it avoids
+ * "? rdf:type T" which can be very unselective. Being data independent, that is
+ * a guess. Consider using the stats matcher for detailed control.
+ */
+public class ReorderFixedAlt extends ReorderTransformationSubstitution
+{
+    public ReorderFixedAlt() {}
+    
+    // Fixed scheme for when we have no stats.
+    // It chooses a triple pattern by order of preference.
+    
+    private static Item type = Item.createNode(NodeConst.nodeRDFType) ;
+    
+    /** The number of triples used for the base scale */
+    public static int MultiTermSampleSize = 100 ; 
+
+    /** Maximum value for a match involving two terms. */
+    public static int MultiTermMax = 9 ; 
+    
+    public final static StatsMatcher matcher ;
+    static {
+        matcher = new StatsMatcher() ;
+        
+        //matcher.addPattern(new Pattern(1,   TERM, TERM, TERM)) ;     // SPO - built-in
- not needed a s a rule
+        
+        // Numbers choosen as an approximation ratios for a graph of 100 triples
+        matcher.addPattern(new Pattern(2,   TERM, TERM, VAR)) ;     // SP?
+        
+        // Pointless - this rule is over ridden by lower weight ?PO
+		// matcher.addPattern(new Pattern(5,   TERM, type, TERM)) ;    // ? type O -- worse than
?PO
+
+        matcher.addPattern(new Pattern(3,   VAR,  TERM, TERM)) ;    // ?PO
+        matcher.addPattern(new Pattern(2,   TERM, VAR,  TERM)) ;    // S?O
+        
+        matcher.addPattern(new Pattern(10,  TERM, VAR,  VAR)) ;     // S??
+        matcher.addPattern(new Pattern(20,  VAR,  VAR,  TERM)) ;    // ??O
+        matcher.addPattern(new Pattern(30,  VAR,  TERM, VAR)) ;     // ?P?
+
+        matcher.addPattern(new Pattern(MultiTermSampleSize, VAR,  VAR,  VAR)) ;     // ???
+    }
+    
+    @Override
+    public double weight(PatternTriple pt)
+    {
+        return matcher.match(pt) ;
+    }
+}


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