Fixed `bool` filter bugs:

* In the case only should clauses were specified with specific type of filters, the first clause determined which documents matched.
 * In some cases the minimum at least 1 should clause should match behaviour was broken.

src/main/java/org/elasticsearch/common/lucene/search/XBooleanFilter.java

@@ -78,10 +78,13 @@ public class XBooleanFilter extends Filter implements Iterable<FilterClause> {
         List<ResultClause> results = new ArrayList<ResultClause>(clauses.size());
         boolean hasShouldClauses = false;
         boolean hasNonEmptyShouldClause = false;
+        boolean hasMustClauses = false;
+        boolean hasMustNotClauses = false;
         for (int i = 0; i < clauses.size(); i++) {
             FilterClause clause = clauses.get(i);
             DocIdSet set = clause.getFilter().getDocIdSet(context, acceptDocs);
             if (clause.getOccur() == Occur.MUST) {
+                hasMustClauses = true;
                 if (DocIdSets.isEmpty(set)) {
                     return null;
                 }
@@ -92,6 +95,7 @@ public class XBooleanFilter extends Filter implements Iterable<FilterClause> {
                 }
                 hasNonEmptyShouldClause = true;
             } else if (clause.getOccur() == Occur.MUST_NOT) {
+                hasMustNotClauses = true;
                 if (DocIdSets.isEmpty(set)) {
                     // we mark empty ones as null for must_not, handle it in the next run...
                     results.add(new ResultClause(null, null, clause));
@@ -110,6 +114,7 @@ public class XBooleanFilter extends Filter implements Iterable<FilterClause> {
         }
 
         // now, go over the clauses and apply the "fast" ones...
+        hasNonEmptyShouldClause = false;
         boolean hasBits = false;
         for (int i = 0; i < results.size(); i++) {
             ResultClause clause = results.get(i);
@@ -123,6 +128,7 @@ public class XBooleanFilter extends Filter implements Iterable<FilterClause> {
                 if (it == null) {
                     continue;
                 }
+                hasNonEmptyShouldClause = true;
                 if (res == null) {
                     res = new FixedBitSet(reader.maxDoc());
                 }
@@ -153,41 +159,41 @@ public class XBooleanFilter extends Filter implements Iterable<FilterClause> {
         }
 
         if (!hasBits) {
+            if (hasShouldClauses && !hasNonEmptyShouldClause) {
+                return null;
+            } else {
                 return res;
             }
+        }
 
         // we have some clauses with bits, apply them...
         // we let the "res" drive the computation, and check Bits for that
+        List<ResultClause> orClauses = new ArrayList<ResultClause>();
         for (int i = 0; i < results.size(); i++) {
             ResultClause clause = results.get(i);
-            // we apply bits in based ones (slow) in the second run
             if (clause.bits == null) {
                 continue;
             }
             if (clause.clause.getOccur() == Occur.SHOULD) {
+                if (hasMustClauses || hasMustNotClauses) {
+                    orClauses.add(clause);
+                } else {
                     if (res == null) {
                         DocIdSetIterator it = clause.docIdSet.iterator();
                         if (it == null) {
                             continue;
                         }
+                        hasNonEmptyShouldClause = true;
                         res = new FixedBitSet(reader.maxDoc());
                         res.or(it);
-                } else {
+                    } else if (!hasMustNotClauses && !hasMustClauses) {
-                    Bits bits = clause.bits;
+                        for (int doc = 0; doc < reader.maxDoc(); doc++) {
-                    // use the "res" to drive the iteration
+                            if (!res.get(doc) && clause.bits.get(doc)) {
-                    int lastSetDoc = res.nextSetBit(0);
+                                hasNonEmptyShouldClause = true;
-                    DocIdSetIterator it = res.iterator();
+                                res.set(doc);
-                    for (int setDoc = it.nextDoc(); setDoc != DocIdSetIterator.NO_MORE_DOCS; setDoc = it.nextDoc()) {
-                        int diff = setDoc - lastSetDoc;
-                        if (diff > 1) {
-                            for (int unsetDoc = lastSetDoc + 1; unsetDoc < setDoc; unsetDoc++) {
-                                if (bits.get(unsetDoc)) {
-                                    res.set(unsetDoc);
                             }
                         }
                     }
-                        lastSetDoc = setDoc;
-                    }
                 }
             } else if (clause.clause.getOccur() == Occur.MUST) {
                 if (res == null) {
@@ -229,9 +235,34 @@ public class XBooleanFilter extends Filter implements Iterable<FilterClause> {
             }
         }
 
+        // From a boolean_logic behavior point of view a should clause doesn't have impact on a bool filter if there
+        // is already a must or must_not clause. However in the current ES bool filter behaviour all should clauses
+        // must match in order for a doc to be a match. What we do here is checking if matched docs match with any
+        // should filter. TODO: Add an option to have disable minimum_should_match=1 behaviour
+        if (!orClauses.isEmpty()) {
+            DocIdSetIterator it = res.iterator();
+            for (int setDoc = it.nextDoc(); setDoc != DocIdSetIterator.NO_MORE_DOCS; setDoc = it.nextDoc()) {
+                boolean match = false;
+                for (ResultClause orClause : orClauses) {
+                    if (orClause.bits.get(setDoc)) {
+                        match = true;
+                        hasNonEmptyShouldClause = true;
+                    }
+                }
+                if (!match) {
+                    res.clear(setDoc);
+                }
+            }
+        }
+
+        if (hasShouldClauses && !hasNonEmptyShouldClause) {
+            return null;
+        } else {
             return res;
         }
 
+    }
+
     /**
      * Adds a new FilterClause to the Boolean Filter container
      *

src/test/java/org/elasticsearch/test/integration/search/query/SimpleQueryTests.java

@@ -1087,4 +1087,61 @@ public class SimpleQueryTests extends AbstractNodesTests {
         assertThat(searchResponse.getHits().getTotalHits(), equalTo(1l));
         assertThat(searchResponse.getHits().getAt(0).getId(), equalTo("1"));
     }
+
+    @Test
+    public void testNumericRangeFilter_2826() throws Exception {
+        client.admin().indices().prepareDelete().execute().actionGet();
+        client.admin().indices().prepareCreate("test").setSettings(
+                ImmutableSettings.settingsBuilder()
+                        .put("index.number_of_shards", 1)
+                        .put("index.number_of_replicas", 0)
+        )
+                .addMapping("type1", jsonBuilder().startObject().startObject("type1").startObject("properties")
+                        .startObject("num_byte").field("type", "byte").endObject()
+                        .startObject("num_short").field("type", "short").endObject()
+                        .startObject("num_integer").field("type", "integer").endObject()
+                        .startObject("num_long").field("type", "long").endObject()
+                        .startObject("num_float").field("type", "float").endObject()
+                        .startObject("num_double").field("type", "double").endObject()
+                        .endObject().endObject().endObject())
+                .execute().actionGet();
+
+        client.prepareIndex("test", "type1", "1").setSource(jsonBuilder().startObject()
+                .field("num_long", 1)
+                .endObject())
+                .execute().actionGet();
+
+        client.prepareIndex("test", "type1", "2").setSource(jsonBuilder().startObject()
+                .field("num_long", 2)
+                .endObject())
+                .execute().actionGet();
+
+        client.prepareIndex("test", "type1", "3").setSource(jsonBuilder().startObject()
+                .field("num_long", 3)
+                .endObject())
+                .execute().actionGet();
+
+        client.prepareIndex("test", "type1", "4").setSource(jsonBuilder().startObject()
+                .field("num_long", 4)
+                .endObject())
+                .execute().actionGet();
+
+        client.admin().indices().prepareRefresh().execute().actionGet();
+        SearchResponse response = client.prepareSearch("test").setFilter(
+                FilterBuilders.boolFilter()
+                        .should(FilterBuilders.rangeFilter("num_long").from(1).to(2))
+                        .should(FilterBuilders.rangeFilter("num_long").from(3).to(4))
+        ).execute().actionGet();
+        assertThat(response.getHits().totalHits(), equalTo(4l));
+
+        // This made 2826 fail! (only with bit based filters)
+        response = client.prepareSearch("test").setFilter(
+                FilterBuilders.boolFilter()
+                        .should(FilterBuilders.numericRangeFilter("num_long").from(1).to(2))
+                        .should(FilterBuilders.numericRangeFilter("num_long").from(3).to(4))
+        ).execute().actionGet();
+
+        assertThat(response.getHits().totalHits(), equalTo(4l));
+    }
+
 }

src/test/java/org/elasticsearch/test/unit/common/lucene/search/XBooleanFilterLuceneTests.java

@@ -0,0 +1,370 @@
+package org.elasticsearch.test.unit.common.lucene.search;
+
+import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.TextField;
+import org.apache.lucene.index.*;
+import org.apache.lucene.queries.FilterClause;
+import org.apache.lucene.queries.TermsFilter;
+import org.apache.lucene.search.*;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.RAMDirectory;
+import org.apache.lucene.util.Bits;
+import org.apache.lucene.util.FixedBitSet;
+import org.elasticsearch.common.lucene.Lucene;
+import org.elasticsearch.common.lucene.search.XBooleanFilter;
+import org.testng.annotations.AfterClass;
+import org.testng.annotations.BeforeClass;
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.IsEqual.equalTo;
+
+/**
+ * Tests ported from Lucene.
+ */
+public class XBooleanFilterLuceneTests {
+    
+    private Directory directory;
+    private AtomicReader reader;
+
+    @BeforeClass
+    public void setUp() throws Exception {
+        directory = new RAMDirectory();
+        IndexWriter writer = new IndexWriter(directory, new IndexWriterConfig(Lucene.VERSION, new WhitespaceAnalyzer(Lucene.VERSION)));
+
+        //Add series of docs with filterable fields : acces rights, prices, dates and "in-stock" flags
+        addDoc(writer, "admin guest", "010", "20040101", "Y");
+        addDoc(writer, "guest", "020", "20040101", "Y");
+        addDoc(writer, "guest", "020", "20050101", "Y");
+        addDoc(writer, "admin", "020", "20050101", "Maybe");
+        addDoc(writer, "admin guest", "030", "20050101", "N");
+        writer.close();
+        reader = new SlowCompositeReaderWrapper(DirectoryReader.open(directory));
+        writer.close();
+    }
+
+    @AfterClass
+    public void tearDown() throws Exception {
+        reader.close();
+        directory.close();
+    }
+
+    private void addDoc(IndexWriter writer, String accessRights, String price, String date, String inStock) throws IOException {
+        Document doc = new Document();
+        doc.add(new TextField("accessRights", accessRights, Field.Store.YES));
+        doc.add(new TextField("price", price, Field.Store.YES));
+        doc.add(new TextField("date", date, Field.Store.YES));
+        doc.add(new TextField("inStock", inStock, Field.Store.YES));
+        writer.addDocument(doc);
+    }
+
+    private Filter getRangeFilter(String field, String lowerPrice, String upperPrice) {
+        return TermRangeFilter.newStringRange(field, lowerPrice, upperPrice, true, true);
+    }
+
+    private Filter getTermsFilter(String field, String text) {
+        return new TermsFilter(new Term(field, text));
+    }
+
+    private Filter getWrappedTermQuery(String field, String text) {
+        return new QueryWrapperFilter(new TermQuery(new Term(field, text)));
+    }
+
+    private Filter getEmptyFilter() {
+        return new Filter() {
+            @Override
+            public DocIdSet getDocIdSet(AtomicReaderContext context, Bits acceptDocs) {
+                return new FixedBitSet(context.reader().maxDoc());
+            }
+        };
+    }
+
+    private Filter getNullDISFilter() {
+        return new Filter() {
+            @Override
+            public DocIdSet getDocIdSet(AtomicReaderContext context, Bits acceptDocs) {
+                return null;
+            }
+        };
+    }
+
+    private Filter getNullDISIFilter() {
+        return new Filter() {
+            @Override
+            public DocIdSet getDocIdSet(AtomicReaderContext context, Bits acceptDocs) {
+                return new DocIdSet() {
+                    @Override
+                    public DocIdSetIterator iterator() {
+                        return null;
+                    }
+
+                    @Override
+                    public boolean isCacheable() {
+                        return true;
+                    }
+                };
+            }
+        };
+    }
+
+    private void tstFilterCard(String mes, int expected, Filter filt) throws Exception {
+        int actual = 0;
+        DocIdSet docIdSet = filt.getDocIdSet(reader.getContext(), reader.getLiveDocs());
+        if (docIdSet != null) {
+            DocIdSetIterator disi = docIdSet.iterator();
+            if (disi != null) {
+                while (disi.nextDoc() != DocIdSetIterator.NO_MORE_DOCS) {
+                    actual++;
+                }
+            }
+        }
+        assertThat(mes, actual, equalTo(expected));
+    }
+
+    @Test
+    public void testShould() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.SHOULD);
+        tstFilterCard("Should retrieves only 1 doc", 1, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getWrappedTermQuery("price", "030"), BooleanClause.Occur.SHOULD);
+        tstFilterCard("Should retrieves only 1 doc", 1, booleanFilter);
+    }
+
+    @Test
+    public void testShoulds() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "010", "020"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getRangeFilter("price", "020", "030"), BooleanClause.Occur.SHOULD);
+        tstFilterCard("Shoulds are Ored together", 5, booleanFilter);
+    }
+
+    @Test
+    public void testShouldsAndMustNot() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "010", "020"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getRangeFilter("price", "020", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("inStock", "N"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("Shoulds Ored but AndNot", 4, booleanFilter);
+
+        booleanFilter.add(getTermsFilter("inStock", "Maybe"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("Shoulds Ored but AndNots", 3, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "010", "020"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getRangeFilter("price", "020", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getWrappedTermQuery("inStock", "N"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("Shoulds Ored but AndNot", 4, booleanFilter);
+
+        booleanFilter.add(getWrappedTermQuery("inStock", "Maybe"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("Shoulds Ored but AndNots", 3, booleanFilter);
+    }
+
+    @Test
+    public void testShouldsAndMust() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "010", "020"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getRangeFilter("price", "020", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard("Shoulds Ored but MUST", 3, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "010", "020"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getRangeFilter("price", "020", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getWrappedTermQuery("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard("Shoulds Ored but MUST", 3, booleanFilter);
+    }
+
+    @Test
+    public void testShouldsAndMusts() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "010", "020"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getRangeFilter("price", "020", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getRangeFilter("date", "20040101", "20041231"), BooleanClause.Occur.MUST);
+        tstFilterCard("Shoulds Ored but MUSTs ANDED", 1, booleanFilter);
+    }
+
+    @Test
+    public void testShouldsAndMustsAndMustNot() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "030", "040"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getRangeFilter("date", "20050101", "20051231"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getTermsFilter("inStock", "N"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("Shoulds Ored but MUSTs ANDED and MustNot", 0, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getRangeFilter("price", "030", "040"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getWrappedTermQuery("accessRights", "admin"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getRangeFilter("date", "20050101", "20051231"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getWrappedTermQuery("inStock", "N"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("Shoulds Ored but MUSTs ANDED and MustNot", 0, booleanFilter);
+    }
+
+    @Test
+    public void testJustMust() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard("MUST", 3, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getWrappedTermQuery("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard("MUST", 3, booleanFilter);
+    }
+
+    @Test
+    public void testJustMustNot() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("inStock", "N"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("MUST_NOT", 4, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getWrappedTermQuery("inStock", "N"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("MUST_NOT", 4, booleanFilter);
+    }
+
+    @Test
+    public void testMustAndMustNot() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("inStock", "N"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("MUST_NOT wins over MUST for same docs", 0, booleanFilter);
+
+        // same with a real DISI (no OpenBitSetIterator)
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getWrappedTermQuery("inStock", "N"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getWrappedTermQuery("price", "030"), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("MUST_NOT wins over MUST for same docs", 0, booleanFilter);
+    }
+
+    @Test
+    public void testEmpty() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        tstFilterCard("empty XBooleanFilter returns no results", 0, booleanFilter);
+    }
+
+    @Test
+    public void testCombinedNullDocIdSets() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.MUST);
+        tstFilterCard("A MUST filter that returns a null DIS should never return documents", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.MUST);
+        tstFilterCard("A MUST filter that returns a null DISI should never return documents", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.SHOULD);
+        tstFilterCard("A SHOULD filter that returns a null DIS should be invisible", 1, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.SHOULD);
+        tstFilterCard("A SHOULD filter that returns a null DISI should be invisible", 1, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("A MUST_NOT filter that returns a null DIS should be invisible", 1, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("price", "030"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("A MUST_NOT filter that returns a null DISI should be invisible", 1, booleanFilter);
+    }
+
+    @Test
+    public void testJustNullDocIdSets() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.MUST);
+        tstFilterCard("A MUST filter that returns a null DIS should never return documents", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.MUST);
+        tstFilterCard("A MUST filter that returns a null DISI should never return documents", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.SHOULD);
+        tstFilterCard("A single SHOULD filter that returns a null DIS should never return documents", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.SHOULD);
+        tstFilterCard("A single SHOULD filter that returns a null DISI should never return documents", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("A single MUST_NOT filter that returns a null DIS should be invisible", 5, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.MUST_NOT);
+        tstFilterCard("A single MUST_NOT filter that returns a null DIS should be invisible", 5, booleanFilter);
+    }
+
+    @Test
+    public void testNonMatchingShouldsAndMusts() throws Exception {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getEmptyFilter(), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard(">0 shoulds with no matches should return no docs", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISFilter(), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard(">0 shoulds with no matches should return no docs", 0, booleanFilter);
+
+        booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getNullDISIFilter(), BooleanClause.Occur.SHOULD);
+        booleanFilter.add(getTermsFilter("accessRights", "admin"), BooleanClause.Occur.MUST);
+        tstFilterCard(">0 shoulds with no matches should return no docs", 0, booleanFilter);
+    }
+
+    @Test
+    public void testToStringOfBooleanFilterContainingTermsFilter() {
+        XBooleanFilter booleanFilter = new XBooleanFilter();
+        booleanFilter.add(getTermsFilter("inStock", "N"), BooleanClause.Occur.MUST);
+        booleanFilter.add(getTermsFilter("isFragile", "Y"), BooleanClause.Occur.MUST);
+
+        assertThat("BooleanFilter(+inStock:N +isFragile:Y)", equalTo(booleanFilter.toString()));
+    }
+
+    @Test
+    public void testToStringOfWrappedBooleanFilters() {
+        XBooleanFilter orFilter = new XBooleanFilter();
+
+        XBooleanFilter stockFilter = new XBooleanFilter();
+        stockFilter.add(new FilterClause(getTermsFilter("inStock", "Y"), BooleanClause.Occur.MUST));
+        stockFilter.add(new FilterClause(getTermsFilter("barCode", "12345678"), BooleanClause.Occur.MUST));
+
+        orFilter.add(new FilterClause(stockFilter, BooleanClause.Occur.SHOULD));
+
+        XBooleanFilter productPropertyFilter = new XBooleanFilter();
+        productPropertyFilter.add(new FilterClause(getTermsFilter("isHeavy", "N"), BooleanClause.Occur.MUST));
+        productPropertyFilter.add(new FilterClause(getTermsFilter("isDamaged", "Y"), BooleanClause.Occur.MUST));
+
+        orFilter.add(new FilterClause(productPropertyFilter, BooleanClause.Occur.SHOULD));
+
+        XBooleanFilter composedFilter = new XBooleanFilter();
+        composedFilter.add(new FilterClause(orFilter, BooleanClause.Occur.MUST));
+
+        assertThat(
+                "BooleanFilter(+BooleanFilter(BooleanFilter(+inStock:Y +barCode:12345678) BooleanFilter(+isHeavy:N +isDamaged:Y)))",
+                equalTo(composedFilter.toString())
+        );
+    }
+
+}

src/test/java/org/elasticsearch/test/unit/common/lucene/search/XBooleanFilterTests.java

@@ -7,6 +7,7 @@ import org.apache.lucene.document.StringField;
 import org.apache.lucene.index.*;
 import org.apache.lucene.queries.FilterClause;
 import org.apache.lucene.search.BooleanClause;
+import org.apache.lucene.search.DocIdSet;
 import org.apache.lucene.search.FieldCacheTermsFilter;
 import org.apache.lucene.search.Filter;
 import org.apache.lucene.store.Directory;
@@ -36,9 +37,9 @@ public class XBooleanFilterTests {
     @BeforeClass
     public void setup() throws Exception {
         char[][] documentMatrix = new char[][] {
-                {'a', 'b', 'c', 'd'},
+                {'a', 'b', 'c', 'd', 'v'},
-                {'a', 'b', 'c', 'd'},
+                {'a', 'b', 'c', 'd', 'z'},
-                {'a', 'a', 'a', 'a'}
+                {'a', 'a', 'a', 'a', 'x'}
         };
 
         List<Document> documents = new ArrayList<Document>(documentMatrix.length);
@@ -218,6 +219,131 @@ public class XBooleanFilterTests {
         }
     }
 
+    @Test
+    public void testOnlyShouldClauses() throws Exception {
+        List<XBooleanFilter> booleanFilters = new ArrayList<XBooleanFilter>();
+        // 2 slow filters
+        // This case caused: https://github.com/elasticsearch/elasticsearch/issues/2826
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(1, 'a', SHOULD, true),
+                newFilterClause(1, 'b', SHOULD, true)
+        ));
+        // 2 fast filters
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(1, 'a', SHOULD, false),
+                newFilterClause(1, 'b', SHOULD, false)
+        ));
+        // 1 fast filters, 1 slow filter
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(1, 'a', SHOULD, true),
+                newFilterClause(1, 'b', SHOULD, false)
+        ));
+
+        for (XBooleanFilter booleanFilter : booleanFilters) {
+            FixedBitSet result = new FixedBitSet(reader.maxDoc());
+            result.or(booleanFilter.getDocIdSet(reader.getContext(), reader.getLiveDocs()).iterator());
+            assertThat(result.cardinality(), equalTo(3));
+            assertThat(result.get(0), equalTo(true));
+            assertThat(result.get(1), equalTo(true));
+            assertThat(result.get(2), equalTo(true));
+        }
+    }
+
+    @Test
+    public void testOnlyMustClauses() throws Exception {
+        List<XBooleanFilter> booleanFilters = new ArrayList<XBooleanFilter>();
+        // Slow filters
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(3, 'd', MUST, true),
+                newFilterClause(3, 'd', MUST, true)
+        ));
+        // 2 fast filters
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(3, 'd', MUST, false),
+                newFilterClause(3, 'd', MUST, false)
+        ));
+        // 1 fast filters, 1 slow filter
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(3, 'd', MUST, true),
+                newFilterClause(3, 'd', MUST, false)
+        ));
+        for (XBooleanFilter booleanFilter : booleanFilters) {
+            FixedBitSet result = new FixedBitSet(reader.maxDoc());
+            result.or(booleanFilter.getDocIdSet(reader.getContext(), reader.getLiveDocs()).iterator());
+            assertThat(result.cardinality(), equalTo(2));
+            assertThat(result.get(0), equalTo(true));
+            assertThat(result.get(1), equalTo(true));
+            assertThat(result.get(2), equalTo(false));
+        }
+    }
+
+    @Test
+    public void testOnlyMustNotClauses() throws Exception {
+        List<XBooleanFilter> booleanFilters = new ArrayList<XBooleanFilter>();
+        // Slow filters
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(1, 'a', MUST_NOT, true),
+                newFilterClause(1, 'a', MUST_NOT, true)
+        ));
+        // 2 fast filters
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(1, 'a', MUST_NOT, false),
+                newFilterClause(1, 'a', MUST_NOT, false)
+        ));
+        // 1 fast filters, 1 slow filter
+        booleanFilters.add(createBooleanFilter(
+                newFilterClause(1, 'a', MUST_NOT, true),
+                newFilterClause(1, 'a', MUST_NOT, false)
+        ));
+        for (XBooleanFilter booleanFilter : booleanFilters) {
+            FixedBitSet result = new FixedBitSet(reader.maxDoc());
+            result.or(booleanFilter.getDocIdSet(reader.getContext(), reader.getLiveDocs()).iterator());
+            assertThat(result.cardinality(), equalTo(2));
+            assertThat(result.get(0), equalTo(true));
+            assertThat(result.get(1), equalTo(true));
+            assertThat(result.get(2), equalTo(false));
+        }
+    }
+
+    @Test
+    public void testNonMatchingSlowShouldWithMatchingMust() throws Exception {
+        XBooleanFilter booleanFilter = createBooleanFilter(
+                newFilterClause(0, 'a', MUST, false),
+                newFilterClause(0, 'b', SHOULD, true)
+        );
+
+        DocIdSet docIdSet = booleanFilter.getDocIdSet(reader.getContext(), reader.getLiveDocs());
+        assertThat(docIdSet, equalTo(null));
+    }
+
+    @Test
+    public void testSlowShouldClause_atLeastOneShouldMustMatch() throws Exception {
+        XBooleanFilter booleanFilter = createBooleanFilter(
+                newFilterClause(0, 'a', MUST, false),
+                newFilterClause(1, 'a', SHOULD, true)
+        );
+
+        FixedBitSet result = new FixedBitSet(reader.maxDoc());
+        result.or(booleanFilter.getDocIdSet(reader.getContext(), reader.getLiveDocs()).iterator());
+        assertThat(result.cardinality(), equalTo(1));
+        assertThat(result.get(0), equalTo(false));
+        assertThat(result.get(1), equalTo(false));
+        assertThat(result.get(2), equalTo(true));
+
+        booleanFilter = createBooleanFilter(
+                newFilterClause(0, 'a', MUST, false),
+                newFilterClause(1, 'a', SHOULD, true),
+                newFilterClause(4, 'z', SHOULD, true)
+        );
+
+        result = new FixedBitSet(reader.maxDoc());
+        result.or(booleanFilter.getDocIdSet(reader.getContext(), reader.getLiveDocs()).iterator());
+        assertThat(result.cardinality(), equalTo(2));
+        assertThat(result.get(0), equalTo(false));
+        assertThat(result.get(1), equalTo(true));
+        assertThat(result.get(2), equalTo(true));
+    }
+
     private static FilterClause newFilterClause(int field, char character, BooleanClause.Occur occur, boolean slowerBitsBackedFilter) {
         Filter filter;
         if (slowerBitsBackedFilter) {