diff --git a/src/test/java/org/elasticsearch/index/search/child/ChildrenConstantScoreQueryTests.java b/src/test/java/org/elasticsearch/index/search/child/ChildrenConstantScoreQueryTests.java
index cad1ff15b05..9dddedd548f 100644
--- a/src/test/java/org/elasticsearch/index/search/child/ChildrenConstantScoreQueryTests.java
+++ b/src/test/java/org/elasticsearch/index/search/child/ChildrenConstantScoreQueryTests.java
@@ -59,7 +59,6 @@ import org.elasticsearch.node.settings.NodeSettingsService;
 import org.elasticsearch.search.internal.ContextIndexSearcher;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.test.ElasticsearchLuceneTestCase;
-import org.elasticsearch.test.cache.recycler.MockBigArrays;
 import org.elasticsearch.test.index.service.StubIndexService;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.hamcrest.Description;
@@ -149,7 +148,7 @@ public class ChildrenConstantScoreQueryTests extends ElasticsearchLuceneTestCase
                 .setMaxBufferedDocs(IndexWriterConfig.DISABLE_AUTO_FLUSH)
                 .setRAMBufferSizeMB(scaledRandomIntBetween(16, 64)); // we might index a lot - don't go crazy here
         RandomIndexWriter indexWriter = new RandomIndexWriter(r, directory, iwc);
-        int numUniqueChildValues = scaledRandomIntBetween(1, 10000);
+        int numUniqueChildValues = scaledRandomIntBetween(100, 2000);
         String[] childValues = new String[numUniqueChildValues];
         for (int i = 0; i < numUniqueChildValues; i++) {
             childValues[i] = Integer.toString(i);
@@ -157,7 +156,7 @@ public class ChildrenConstantScoreQueryTests extends ElasticsearchLuceneTestCase
 
         IntOpenHashSet filteredOrDeletedDocs = new IntOpenHashSet();
         int childDocId = 0;
-        int numParentDocs = scaledRandomIntBetween(1, 2000);
+        int numParentDocs = scaledRandomIntBetween(1, numUniqueChildValues);
         ObjectObjectOpenHashMap<String, NavigableSet<String>> childValueToParentIds = new ObjectObjectOpenHashMap<>();
         for (int parentDocId = 0; parentDocId < numParentDocs; parentDocId++) {
             boolean markParentAsDeleted = rarely();
diff --git a/src/test/java/org/elasticsearch/index/search/child/ChildrenQueryTests.java b/src/test/java/org/elasticsearch/index/search/child/ChildrenQueryTests.java
index 6c0a55d5ef8..e5386823d26 100644
--- a/src/test/java/org/elasticsearch/index/search/child/ChildrenQueryTests.java
+++ b/src/test/java/org/elasticsearch/index/search/child/ChildrenQueryTests.java
@@ -21,6 +21,7 @@ package org.elasticsearch.index.search.child;
 import com.carrotsearch.hppc.FloatArrayList;
 import com.carrotsearch.hppc.IntOpenHashSet;
 import com.carrotsearch.hppc.ObjectObjectOpenHashMap;
+import org.apache.lucene.analysis.MockAnalyzer;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.StringField;
@@ -29,6 +30,7 @@ import org.apache.lucene.queries.TermFilter;
 import org.apache.lucene.search.*;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.FixedBitSet;
+import org.apache.lucene.util.LuceneTestCase;
 import org.elasticsearch.common.lucene.search.NotFilter;
 import org.elasticsearch.common.lucene.search.XFilteredQuery;
 import org.elasticsearch.index.engine.Engine;
@@ -48,6 +50,7 @@ import org.junit.Test;
 import java.io.IOException;
 import java.util.Map;
 import java.util.NavigableMap;
+import java.util.Random;
 import java.util.TreeMap;
 
 import static org.elasticsearch.index.search.child.ChildrenConstantScoreQueryTests.assertBitSet;
@@ -81,8 +84,13 @@ public class ChildrenQueryTests extends ElasticsearchLuceneTestCase {
     @Test
     public void testRandom() throws Exception {
         Directory directory = newDirectory();
-        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
-        int numUniqueChildValues = 1 + random().nextInt(TEST_NIGHTLY ? 6000 : 600);
+        final Random r = random();
+        final IndexWriterConfig iwc = LuceneTestCase.newIndexWriterConfig(r,
+                LuceneTestCase.TEST_VERSION_CURRENT, new MockAnalyzer(r))
+                .setMaxBufferedDocs(IndexWriterConfig.DISABLE_AUTO_FLUSH)
+                .setRAMBufferSizeMB(scaledRandomIntBetween(16, 64)); // we might index a lot - don't go crazy here
+        RandomIndexWriter indexWriter = new RandomIndexWriter(r, directory, iwc);
+        int numUniqueChildValues = scaledRandomIntBetween(100, 2000);
         String[] childValues = new String[numUniqueChildValues];
         for (int i = 0; i < numUniqueChildValues; i++) {
             childValues[i] = Integer.toString(i);
@@ -91,7 +99,7 @@ public class ChildrenQueryTests extends ElasticsearchLuceneTestCase {
         IntOpenHashSet filteredOrDeletedDocs = new IntOpenHashSet();
 
         int childDocId = 0;
-        int numParentDocs = 1 + random().nextInt(TEST_NIGHTLY ? 20000 : 1000);
+        int numParentDocs = scaledRandomIntBetween(1, numUniqueChildValues);
         ObjectObjectOpenHashMap<String, NavigableMap<String, FloatArrayList>> childValueToParentIds = new ObjectObjectOpenHashMap<>();
         for (int parentDocId = 0; parentDocId < numParentDocs; parentDocId++) {
             boolean markParentAsDeleted = rarely();
@@ -110,12 +118,7 @@ public class ChildrenQueryTests extends ElasticsearchLuceneTestCase {
             }
             indexWriter.addDocument(document);
 
-            int numChildDocs;
-            if (rarely()) {
-                numChildDocs = random().nextInt(TEST_NIGHTLY ? 100 : 25);
-            } else {
-                numChildDocs = random().nextInt(TEST_NIGHTLY ? 40 : 10);
-            }
+            int numChildDocs = scaledRandomIntBetween(0, 100);
             for (int i = 0; i < numChildDocs; i++) {
                 boolean markChildAsDeleted = rarely();
                 String childValue = childValues[random().nextInt(childValues.length)];
diff --git a/src/test/java/org/elasticsearch/index/search/child/ParentConstantScoreQueryTests.java b/src/test/java/org/elasticsearch/index/search/child/ParentConstantScoreQueryTests.java
index aa9b8d5be25..127a4ba6196 100644
--- a/src/test/java/org/elasticsearch/index/search/child/ParentConstantScoreQueryTests.java
+++ b/src/test/java/org/elasticsearch/index/search/child/ParentConstantScoreQueryTests.java
@@ -88,14 +88,14 @@ public class ParentConstantScoreQueryTests extends ElasticsearchLuceneTestCase {
                 .setMaxBufferedDocs(IndexWriterConfig.DISABLE_AUTO_FLUSH)
                 .setRAMBufferSizeMB(scaledRandomIntBetween(16, 64)); // we might index a lot - don't go crazy here
         RandomIndexWriter indexWriter = new RandomIndexWriter(r, directory, iwc);
-        int numUniqueParentValues = scaledRandomIntBetween(1, 1000);
+        int numUniqueParentValues = scaledRandomIntBetween(100, 2000);
         String[] parentValues = new String[numUniqueParentValues];
         for (int i = 0; i < numUniqueParentValues; i++) {
             parentValues[i] = Integer.toString(i);
         }
 
         int childDocId = 0;
-        int numParentDocs = scaledRandomIntBetween(1, 2000);
+        int numParentDocs = scaledRandomIntBetween(1, numUniqueParentValues);
         ObjectObjectOpenHashMap<String, NavigableSet<String>> parentValueToChildDocIds = new ObjectObjectOpenHashMap<>();
         IntIntOpenHashMap childIdToParentId = new IntIntOpenHashMap();
         for (int parentDocId = 0; parentDocId < numParentDocs; parentDocId++) {
diff --git a/src/test/java/org/elasticsearch/index/search/child/ParentQueryTests.java b/src/test/java/org/elasticsearch/index/search/child/ParentQueryTests.java
index 7c09e5ed16c..f86e4815809 100644
--- a/src/test/java/org/elasticsearch/index/search/child/ParentQueryTests.java
+++ b/src/test/java/org/elasticsearch/index/search/child/ParentQueryTests.java
@@ -21,6 +21,7 @@ package org.elasticsearch.index.search.child;
 import com.carrotsearch.hppc.FloatArrayList;
 import com.carrotsearch.hppc.IntIntOpenHashMap;
 import com.carrotsearch.hppc.ObjectObjectOpenHashMap;
+import org.apache.lucene.analysis.MockAnalyzer;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.StringField;
@@ -29,6 +30,7 @@ import org.apache.lucene.queries.TermFilter;
 import org.apache.lucene.search.*;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.FixedBitSet;
+import org.apache.lucene.util.LuceneTestCase;
 import org.elasticsearch.common.lucene.search.NotFilter;
 import org.elasticsearch.common.lucene.search.XFilteredQuery;
 import org.elasticsearch.index.engine.Engine;
@@ -47,6 +49,7 @@ import org.junit.Test;
 import java.io.IOException;
 import java.util.Map;
 import java.util.NavigableMap;
+import java.util.Random;
 import java.util.TreeMap;
 
 import static org.elasticsearch.index.search.child.ChildrenConstantScoreQueryTests.assertBitSet;
@@ -79,15 +82,20 @@ public class ParentQueryTests extends ElasticsearchLuceneTestCase {
     @Test
     public void testRandom() throws Exception {
         Directory directory = newDirectory();
-        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
-        int numUniqueParentValues = 1 + random().nextInt(TEST_NIGHTLY ? 6000 : 600);
+        final Random r = random();
+        final IndexWriterConfig iwc = LuceneTestCase.newIndexWriterConfig(r,
+                LuceneTestCase.TEST_VERSION_CURRENT, new MockAnalyzer(r))
+                .setMaxBufferedDocs(IndexWriterConfig.DISABLE_AUTO_FLUSH)
+                .setRAMBufferSizeMB(scaledRandomIntBetween(16, 64)); // we might index a lot - don't go crazy here
+        RandomIndexWriter indexWriter = new RandomIndexWriter(r, directory, iwc);
+        int numUniqueParentValues = scaledRandomIntBetween(100, 2000);
         String[] parentValues = new String[numUniqueParentValues];
         for (int i = 0; i < numUniqueParentValues; i++) {
             parentValues[i] = Integer.toString(i);
         }
 
         int childDocId = 0;
-        int numParentDocs = 1 + random().nextInt(TEST_NIGHTLY ? 20000 : 1000);
+        int numParentDocs = scaledRandomIntBetween(1, numUniqueParentValues);
         ObjectObjectOpenHashMap<String, NavigableMap<String, Float>> parentValueToChildIds = new ObjectObjectOpenHashMap<>();
         IntIntOpenHashMap childIdToParentId = new IntIntOpenHashMap();
         for (int parentDocId = 0; parentDocId < numParentDocs; parentDocId++) {
@@ -103,12 +111,7 @@ public class ParentQueryTests extends ElasticsearchLuceneTestCase {
             }
             indexWriter.addDocument(document);
 
-            int numChildDocs;
-            if (rarely()) {
-                numChildDocs = random().nextInt(TEST_NIGHTLY ? 100 : 25);
-            } else {
-                numChildDocs = random().nextInt(TEST_NIGHTLY ? 40 : 10);
-            }
+            int numChildDocs = scaledRandomIntBetween(0, 100);
             if (parentDocId == numParentDocs - 1 && childIdToParentId.isEmpty()) {
                 // ensure there is at least one child in the index
                 numChildDocs = Math.max(1, numChildDocs);
@@ -181,7 +184,7 @@ public class ParentQueryTests extends ElasticsearchLuceneTestCase {
 
             // Simulate a child update
             if (random().nextBoolean()) {
-                int numberOfUpdates = 1 + random().nextInt(TEST_NIGHTLY ? 25 : 5);
+                int numberOfUpdates = scaledRandomIntBetween(1, 5);
                 int[] childIds = childIdToParentId.keys().toArray();
                 for (int j = 0; j < numberOfUpdates; j++) {
                     int childId = childIds[random().nextInt(childIds.length)];