Github user anoopsjohn commented on a diff in the pull request:
https://github.com/apache/incubator-phoenix/pull/30#discussion_r13238970
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/util/FirstLastNthValueDataContainer.java
---
@@ -0,0 +1,168 @@
+/*
+ * 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.
+ */
+package org.apache.phoenix.util;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.TreeMap;
+import org.apache.hadoop.hbase.util.Bytes;
+
+/**
+ * Container for data transfer between server and client aggregation
(FIRST|LAST|NTH)_VALUE functions
+ *
+ */
+public class FirstLastNthValueDataContainer {
+
+ protected boolean isAscending = false;
+ protected int offset;
+ protected TreeMap<byte[], byte[]> data;
+ protected boolean isOrderValuesFixedLength = false;
+ protected boolean isDataValuesFixedLength = false;
+
+ public void setIsAscending(boolean ascending) {
+ isAscending = ascending;
+ }
+
+ public void setData(TreeMap<byte[], byte[]> topValues) {
+ data = topValues;
+ }
+
+ public void setFixedWidthOrderValues(boolean fixedSize) {
+ isOrderValuesFixedLength = fixedSize;
+ }
+
+ public void setFixedWidthDataValues(boolean fixedSize) {
+ isDataValuesFixedLength = fixedSize;
+ }
+
+ public void setOffset(int offset) {
+ this.offset = offset;
+ }
+
+ public void setPayload(byte[] payload) {
+ if (payload[0] == (byte) 1) {
+ isAscending = true;
+ }
+
+ int lengthOfOrderValues = Bytes.toInt(payload, 1);
+ int lengthOfDataValues = Bytes.toInt(payload, 5);
+ int sizeOfMap = Bytes.toInt(payload, 9);
+
+ data = new TreeMap<byte[], byte[]>(new
Bytes.ByteArrayComparator());
+
+ int payloadOffset = 13;
+
+ for (; sizeOfMap != 0; sizeOfMap--) {
+ byte[] key;
+ byte[] value;
+
+ if (lengthOfOrderValues != 0) {
+ key = Bytes.copy(payload, payloadOffset,
lengthOfOrderValues);
+ payloadOffset += lengthOfOrderValues;
+ } else {
+ int l = Bytes.toInt(payload, payloadOffset);
+ payloadOffset += 4;
+ key = Bytes.copy(payload, payloadOffset, l);
+ payloadOffset += l;
+ }
+
+ if (lengthOfDataValues != 0) {
+ value = Bytes.copy(payload, payloadOffset,
lengthOfDataValues);
+ payloadOffset += lengthOfDataValues;
+ } else {
+ int l = Bytes.toInt(payload, payloadOffset);
+ payloadOffset += 4;
+ value = Bytes.copy(payload, payloadOffset, l);
+ payloadOffset += l;
+ }
+
+ data.put(key, value);
+ }
+
+ }
+
+ public byte[] getPayload() throws IOException {
+ /*
+ PAYLOAD STUCTURE
+
+ what | size (bytes) | info
+ is ascending | 1 | 1 = asc, 0 = desc
+ length of order by vals | 4 | 0 if dynamic length, size
otherwise
+ length of values | 4 | 0 if dynamic length, size
otherwise
+ [ lenght of first order | 4 | set if order is var
length (optional) ]
+ first order value | n | order by val
+ [ lenght of first value | 4 | set if value is var
length (optional) ]
+ first order value | n | data val
+ ... and so on, repeat order by values and data values
+
+
+ example with fixed length for data and order by values
+ 0 | 0000 0004 | 0000 0004 | 0000 0001
| 0000 000FF | ...
+ is ascendig | length order vals | length data vals | first order
val | first value | ... more values
+
+ example with dynamic length for data (length will be zeros)
+ 0 | 0000 0000 | 0000 0000 | 0000 0004
| 0000 000FF | ...
+ is ascendig | length order vals | length data vals | first order
length | first order value | ... more values
+
+ */
+
+ ByteArrayOutputStream bos = new ByteArrayOutputStream();
+
+ bos.write(isAscending ? (byte) 1 : (byte) 0);
+
+ Entry<byte[], byte[]> firstEntry = data.firstEntry();
+ if (isOrderValuesFixedLength) {
--- End diff --
Good..
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