docs/attachments/LUCENE-5816/LUCENE-5816.patch

diff --git a/lucene/join/src/java/org/apache/lucene/search/join/ToParentBlockJoinQuery.java b/lucene/join/src/java/org/apache/lucene/search/join/ToParentBlockJoinQuery.java
index f6985e2..b67dbd8 100644
--- a/lucene/join/src/java/org/apache/lucene/search/join/ToParentBlockJoinQuery.java
+++ b/lucene/join/src/java/org/apache/lucene/search/join/ToParentBlockJoinQuery.java
@@ -60,10 +60,6 @@ import org.apache.lucene.util.FixedBitSet;
  * <p>See {@link ToChildBlockJoinQuery} if you need to join
  * in the reverse order.
  *
- * <p>The child documents must be orthogonal to the parent
- * documents: the wrapped child query must never
- * return a parent document.</p>
- *
  * If you'd like to retrieve {@link TopGroups} for the
  * resulting query, use the {@link ToParentBlockJoinCollector}.
  * Note that this is not necessary, ie, if you simply want
@@ -280,12 +276,6 @@ public class ToParentBlockJoinQuery extends Query {
 
         parentDoc = parentBits.nextSetBit(nextChildDoc);
 
-        // Parent & child docs are supposed to be
-        // orthogonal:
-        if (nextChildDoc == parentDoc) {
-          throw new IllegalStateException("child query must only match non-parent docs, but parent docID=" + nextChildDoc + " matched childScorer=" + childScorer.getClass());
-        }
-
         //System.out.println("  parentDoc=" + parentDoc);
         assert parentDoc != -1;
 
@@ -295,13 +285,7 @@ public class ToParentBlockJoinQuery extends Query {
           // we hit a new parent doc:
           do {
             nextChildDoc = childScorer.nextDoc();
-          } while (nextChildDoc < parentDoc);
-
-          // Parent & child docs are supposed to be
-          // orthogonal:
-          if (nextChildDoc == parentDoc) {
-            throw new IllegalStateException("child query must only match non-parent docs, but parent docID=" + nextChildDoc + " matched childScorer=" + childScorer.getClass());
-          }
+          } while (nextChildDoc <= parentDoc);
 
           continue;
         }
@@ -336,13 +320,7 @@ public class ToParentBlockJoinQuery extends Query {
           }
           childDocUpto++;
           nextChildDoc = childScorer.nextDoc();
-        } while (nextChildDoc < parentDoc);
-
-        // Parent & child docs are supposed to be
-        // orthogonal:
-        if (nextChildDoc == parentDoc) {
-          throw new IllegalStateException("child query must only match non-parent docs, but parent docID=" + nextChildDoc + " matched childScorer=" + childScorer.getClass());
-        }
+        } while (nextChildDoc <= parentDoc);
 
         switch(scoreMode) {
         case Avg:
@@ -400,18 +378,13 @@ public class ToParentBlockJoinQuery extends Query {
 
       //System.out.println("  rolled back to prevParentDoc=" + prevParentDoc + " vs parentDoc=" + parentDoc);
       assert prevParentDoc >= parentDoc;
-      if (prevParentDoc > nextChildDoc) {
-        nextChildDoc = childScorer.advance(prevParentDoc);
+      if (prevParentDoc >= nextChildDoc) {
+        nextChildDoc = childScorer.advance(prevParentDoc + 1);
         // System.out.println("  childScorer advanced to child docID=" + nextChildDoc);
       //} else {
         //System.out.println("  skip childScorer advance");
       }
 
-      // Parent & child docs are supposed to be orthogonal:
-      if (nextChildDoc == prevParentDoc) {
-        throw new IllegalStateException("child query must only match non-parent docs, but parent docID=" + nextChildDoc + " matched childScorer=" + childScorer.getClass());
-      }
-
       final int nd = nextDoc();
       //System.out.println("  return nextParentDoc=" + nd);
       return nd;
diff --git a/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoin.java b/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoin.java
index 1e6c477..e841369 100644
--- a/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoin.java
+++ b/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoin.java
@@ -1389,7 +1389,6 @@ public class TestBlockJoin extends LuceneTestCase {
     d.close();
   }
 
-  // LUCENE-4968
   public void testChildQueryMatchesParent() throws Exception {
     Directory d = newDirectory();
     RandomIndexWriter w = new RandomIndexWriter(random(), d);
@@ -1423,7 +1422,7 @@ public class TestBlockJoin extends LuceneTestCase {
     IndexReader r = w.getReader();
     w.close();
 
-    // illegally matches parent:
+    // childQuery matches parent:
     Query childQuery = new TermQuery(new Term("parentText", "text"));
     Filter parentsFilter = new FixedBitSetCachingWrapperFilter(new QueryWrapperFilter(new TermQuery(new Term("isParent", "yes"))));
     ToParentBlockJoinQuery childJoinQuery = new ToParentBlockJoinQuery(childQuery, parentsFilter, ScoreMode.Avg);
@@ -1434,13 +1433,19 @@ public class TestBlockJoin extends LuceneTestCase {
     ToParentBlockJoinCollector c = new ToParentBlockJoinCollector(new Sort(new SortField("parentID", SortField.Type.STRING)),
                                                                   10, true, true);
 
-    try {
-      newSearcher(r).search(parentQuery, c);
-      fail("should have hit exception");
-    } catch (IllegalStateException ise) {
-      // expected
-    }
+    newSearcher(r).search(parentQuery, c);
+    TopGroups<Integer> groups = c.getTopGroups(childJoinQuery, null, 0, 10, 0, false);
+
+    // Two parents:
+    assertEquals(2, groups.totalGroupCount.intValue());
 
+    GroupDocs<Integer> group = groups.groups[0];
+    Document doc = r.document(group.groupValue.intValue());
+    assertEquals("0", doc.get("parentID"));
+
+    group = groups.groups[1];
+    doc = r.document(group.groupValue.intValue());
+    assertEquals("1", doc.get("parentID"));
     r.close();
     d.close();
   }
diff --git a/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoinValidation.java b/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoinValidation.java
index a2b6360..bb574cd 100644
--- a/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoinValidation.java
+++ b/lucene/join/src/test/org/apache/lucene/search/join/TestBlockJoinValidation.java
@@ -76,34 +76,6 @@ public class TestBlockJoinValidation extends LuceneTestCase {
   }
 
   @Test
-  public void testNextDocValidationForToParentBjq() throws Exception {
-    Query parentQueryWithRandomChild = createChildrenQueryWithOneParent(getRandomChildNumber(0));
-    ToParentBlockJoinQuery blockJoinQuery = new ToParentBlockJoinQuery(parentQueryWithRandomChild, parentsFilter, ScoreMode.None);
-    thrown.expect(IllegalStateException.class);
-    thrown.expectMessage("child query must only match non-parent docs");
-    indexSearcher.search(blockJoinQuery, 1);
-  }
-
-  @Test
-  public void testAdvanceValidationForToParentBjq() throws Exception {
-    int randomChildNumber = getRandomChildNumber(0);
-    // we need to make advance method meet wrong document, so random child number
-    // in BJQ must be greater than child number in Boolean clause
-    int nextRandomChildNumber = getRandomChildNumber(randomChildNumber);
-    Query parentQueryWithRandomChild = createChildrenQueryWithOneParent(nextRandomChildNumber);
-    ToParentBlockJoinQuery blockJoinQuery = new ToParentBlockJoinQuery(parentQueryWithRandomChild, parentsFilter, ScoreMode.None);
-    // advance() method is used by ConjunctionScorer, so we need to create Boolean conjunction query
-    BooleanQuery conjunctionQuery = new BooleanQuery();
-    WildcardQuery childQuery = new WildcardQuery(new Term("child", createFieldValue(randomChildNumber)));
-    conjunctionQuery.add(new BooleanClause(childQuery, BooleanClause.Occur.MUST));
-    conjunctionQuery.add(new BooleanClause(blockJoinQuery, BooleanClause.Occur.MUST));
-
-    thrown.expect(IllegalStateException.class);
-    thrown.expectMessage("child query must only match non-parent docs");
-    indexSearcher.search(conjunctionQuery, 1);
-  }
-
-  @Test
   public void testNextDocValidationForToChildBjq() throws Exception {
     Query parentQueryWithRandomChild = createParentsQueryWithOneChild(getRandomChildNumber(0));