svn commit: r1516654 - /incubator/vxquery/trunk/vxquery/vxquery-core/src/main/java/org/apache/vxquery/compiler/rewriter/RewriteRuleset.java

[pr...@apache.org]

Author: prestonc
Date: Thu Aug 22 22:54:41 2013
New Revision: 1516654

URL: http://svn.apache.org/r1516654
Log:
Added more comments about each rewrite step and added a new rule (EliminateUnnestAggregateSequencesRule).

Modified:
    incubator/vxquery/trunk/vxquery/vxquery-core/src/main/java/org/apache/vxquery/compiler/rewriter/RewriteRuleset.java

Modified: incubator/vxquery/trunk/vxquery/vxquery-core/src/main/java/org/apache/vxquery/compiler/rewriter/RewriteRuleset.java
URL: http://svn.apache.org/viewvc/incubator/vxquery/trunk/vxquery/vxquery-core/src/main/java/org/apache/vxquery/compiler/rewriter/RewriteRuleset.java?rev=1516654&r1=1516653&r2=1516654&view=diff
==============================================================================
--- incubator/vxquery/trunk/vxquery/vxquery-core/src/main/java/org/apache/vxquery/compiler/rewriter/RewriteRuleset.java (original)
+++ incubator/vxquery/trunk/vxquery/vxquery-core/src/main/java/org/apache/vxquery/compiler/rewriter/RewriteRuleset.java Thu Aug 22 22:54:41 2013
@@ -23,6 +23,7 @@ import org.apache.vxquery.compiler.rewri
 import org.apache.vxquery.compiler.rewriter.rules.ConvertAssignSortDistinctNodesToOperatorsRule;
 import org.apache.vxquery.compiler.rewriter.rules.ConvertAssignToAggregateRule;
 import org.apache.vxquery.compiler.rewriter.rules.EliminateSubplanForSinglePathsRule;
+import org.apache.vxquery.compiler.rewriter.rules.EliminateUnnestAggregateSequencesRule;
 import org.apache.vxquery.compiler.rewriter.rules.EliminateUnnestAggregateSubplanRule;
 import org.apache.vxquery.compiler.rewriter.rules.InlineReferenceVariablePolicy;
 import org.apache.vxquery.compiler.rewriter.rules.IntroduceCollectionRule;
@@ -64,29 +65,43 @@ public class RewriteRuleset {
         List<IAlgebraicRewriteRule> normalization = new LinkedList<IAlgebraicRewriteRule>();
         normalization.add(new SetVariableIdContextRule());
 
+        // Remove unused functions.
         normalization.add(new RemoveUnusedSortDistinctNodesRule());
         normalization.add(new InlineVariablesRule(new InlineReferenceVariablePolicy()));
         normalization.add(new RemoveUnusedAssignAndAggregateRule());
+
         // TODO Fix the group by operator before putting back in the rule set.
-//        normalization.add(new ConvertAssignSortDistinctNodesToOperatorsRule());
+        //        normalization.add(new ConvertAssignSortDistinctNodesToOperatorsRule());
 
+        // Find assign for scalar aggregate function followed by an aggregate operator.
         normalization.add(new ConsolidateAssignAggregateRule());
         normalization.add(new InlineVariablesRule(new InlineReferenceVariablePolicy()));
         normalization.add(new RemoveUnusedAssignAndAggregateRule());
-        
+
+        // Find assign for scalar aggregate function.
         normalization.add(new ConvertAssignToAggregateRule());
 
+        // Find unnest followed by aggregate in a subplan. 
         normalization.add(new EliminateUnnestAggregateSubplanRule());
         normalization.add(new InlineVariablesRule(new InlineReferenceVariablePolicy()));
         normalization.add(new RemoveUnusedAssignAndAggregateRule());
-        
+
+        // Remove single tuple input subplans and merge unnest aggregate operators.
         normalization.add(new EliminateSubplanForSinglePathsRule());
+        normalization.add(new EliminateUnnestAggregateSequencesRule());
 
+        // Convert to a data source scan operator.
         normalization.add(new SetCollectionDataSourceRule());
         normalization.add(new IntroduceCollectionRule());
         normalization.add(new RemoveUnusedAssignAndAggregateRule());
 
+        // Use two step aggregate operators if possible.
         normalization.add(new IntroduceTwoStepAggregateRule());
+
+        // Used to clean up any missing noops after all the subplans have been altered.
+        normalization.add(new InlineVariablesRule(new InlineReferenceVariablePolicy()));
+        normalization.add(new RemoveUnusedAssignAndAggregateRule());
+
         return normalization;
     }