optimize a filtered query with match_all query into a constant score that just wraps the filter

Author: kimchy

modules/elasticsearch/src/main/java/org/elasticsearch/common/lucene/search/Queries.java

@@ -87,4 +87,17 @@ public static Query fixNegativeQueryIfNeeded(Query q) {
         }
         return q;
     }
+
+    public static boolean isMatchAllQuery(Query query) {
+        if (query instanceof MatchAllDocsQuery) {
+            return true;
+        }
+        if (query instanceof DeletionAwareConstantScoreQuery) {
+            DeletionAwareConstantScoreQuery scoreQuery = (DeletionAwareConstantScoreQuery) query;
+            if (scoreQuery.getFilter() instanceof MatchAllDocsFilter) {
+                return true;
+            }
+        }
+        return false;
+    }
 }

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/xcontent/FilteredQueryParser.java

@@ -19,10 +19,12 @@
 
 package org.elasticsearch.index.query.xcontent;
 
+import org.apache.lucene.search.DeletionAwareConstantScoreQuery;
 import org.apache.lucene.search.Filter;
 import org.apache.lucene.search.FilteredQuery;
 import org.apache.lucene.search.Query;
 import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.lucene.search.Queries;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.AbstractIndexComponent;
@@ -86,6 +88,13 @@ public class FilteredQueryParser extends AbstractIndexComponent implements XCont
             filter = parseContext.cacheFilter(filter);
         }
 
+        // if its a match_all query, use constant_score
+        if (Queries.isMatchAllQuery(query)) {
+            Query q = new DeletionAwareConstantScoreQuery(filter);
+            q.setBoost(boost);
+            return q;
+        }
+
         // TODO
         // With the way filtered queries work today, both query and filter advance (one at a time)
         // to get hits. Since all filters support random access, it might make sense to use that.
@@ -96,6 +105,7 @@ public class FilteredQueryParser extends AbstractIndexComponent implements XCont
         //    - https://issues.apache.org/jira/browse/LUCENE-1536
         //    - http://chbits.blogspot.com/2010/09/fast-search-filters-using-flex.html
 
+
         FilteredQuery filteredQuery = new FilteredQuery(query, filter);
         filteredQuery.setBoost(boost);
         return filteredQuery;

modules/elasticsearch/src/main/java/org/elasticsearch/search/facet/query/QueryFacetCollector.java

@@ -20,10 +20,13 @@
 package org.elasticsearch.search.facet.query;
 
 import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.search.*;
+import org.apache.lucene.search.Filter;
+import org.apache.lucene.search.FilteredQuery;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.QueryWrapperFilter;
 import org.elasticsearch.common.lucene.docset.DocSet;
 import org.elasticsearch.common.lucene.docset.DocSets;
-import org.elasticsearch.common.lucene.search.MatchAllDocsFilter;
+import org.elasticsearch.common.lucene.search.Queries;
 import org.elasticsearch.index.cache.filter.FilterCache;
 import org.elasticsearch.search.facet.AbstractFacetCollector;
 import org.elasticsearch.search.facet.Facet;
@@ -71,15 +74,9 @@ public QueryFacetCollector(String facetName, Query query, FilterCache filterCach
     private Filter extractFilterIfApplicable(Query query) {
         if (query instanceof FilteredQuery) {
             FilteredQuery fQuery = (FilteredQuery) query;
-            if (fQuery.getQuery() instanceof MatchAllDocsQuery) {
+            if (Queries.isMatchAllQuery(fQuery.getQuery())) {
                 return fQuery.getFilter();
             }
-            if (fQuery.getQuery() instanceof DeletionAwareConstantScoreQuery) {
-                DeletionAwareConstantScoreQuery scoreQuery = (DeletionAwareConstantScoreQuery) fQuery.getQuery();
-                if (scoreQuery.getFilter() instanceof MatchAllDocsFilter) {
-                    return fQuery.getFilter();
-                }
-            }
         }
         return null;
     }