Github user bitblender commented on a diff in the pull request:
https://github.com/apache/drill/pull/914#discussion_r137852118
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/rowSet/impl/package-info.java
---
@@ -0,0 +1,295 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Handles the details of the result set loader implementation.
+ * <p>
+ * The primary purpose of this loader, and the most complex to understand
and
+ * maintain, is overflow handling.
+ *
+ * <h4>Detailed Use Cases</h4>
+ *
+ * Let's examine it by considering a number of
+ * use cases.
+ * <table style="border: 1px solid; border-collapse: collapse;">
+ *
<tr><th>Row</th><th>a</th><th>b</th><th>c</th><th>d</th><th>e</th><th>f</th><th>g</th><th>h</th></tr>
+ *
<tr><td>n-2</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>-</td><td>-</td></tr>
+ * <tr><td>n-1</td><td>X</td><td>X</td><td>X</td><td>X</td><td> </td><td>
</td><td>-</td><td>-</td></tr>
+ * <tr><td>n </td><td>X</td><td>!</td><td>O</td><td> </td><td>O</td><td>
</td><td>O</td><td> </td></tr>
+ * </table>
+ * Here:
+ * <ul>
+ * <li>n-2, n-1, and n are rows. n is the overflow row.</li>
+ * <li>X indicates a value was written before overflow.</li>
+ * <li>Blank indicates no value was written in that row.</li>
+ * <li>! indicates the value that triggered overflow.</li>
+ * <li>- indicates a column that did not exist prior to overflow.</li>
--- End diff --
What does an 'O' value mean in the diagram above?
---
