Github user anoopsjohn commented on a diff in the pull request:
https://github.com/apache/incubator-phoenix/pull/30#discussion_r12086460
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/expression/aggregator/FirstLastValueServerAggregator.java
---
@@ -0,0 +1,196 @@
+/*
+ * 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.expression.aggregator;
+
+import org.apache.phoenix.expression.Expression;
+import org.apache.phoenix.schema.PDataType;
+import org.apache.phoenix.schema.tuple.Tuple;
+import org.apache.phoenix.util.BinarySerializableComparator;
+import org.apache.phoenix.util.ByteUtil;
+import org.apache.phoenix.util.FirstLastValueDataContainer;
+import org.apache.phoenix.util.FirstLastValueOffsetDataContainer;
+import org.apache.phoenix.util.SizedUtil;
+import java.io.IOException;
+import java.util.List;
+import java.util.TreeMap;
+import org.apache.hadoop.hbase.filter.BinaryComparator;
+import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.phoenix.schema.SortOrder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Base server aggregator for FIRST|LAST VALUE functions
+ *
+ */
+public class FirstLastValueServerAggregator extends BaseAggregator {
+
+ private static final Logger logger =
LoggerFactory.getLogger(FirstLastValueServerAggregator.class);
+ protected List<Expression> children;
+ protected BinaryComparator topOrder = new
BinaryComparator(ByteUtil.EMPTY_BYTE_ARRAY);
+ protected byte[] topValue;
+ protected boolean useOffset = false;
+ protected int offset = -1;
+ protected TreeMap<byte[], byte[]> topValues = new TreeMap<byte[],
byte[]>(new BinarySerializableComparator());
+ protected boolean isAscending;
+
+ public FirstLastValueServerAggregator() {
+ super(SortOrder.getDefault());
+ }
+
+ @Override
+ public void reset() {
+ topOrder = new BinaryComparator(ByteUtil.EMPTY_BYTE_ARRAY);
+ topValue = null;
+ topValues.clear();
+ offset = -1;
+ useOffset = false;
+
+ super.reset();
+ }
+
+ @Override
+ public int getSize() {
+ return super.getSize() +
SizedUtil.IMMUTABLE_BYTES_WRITABLE_SIZE;
+ }
+
+ @Override
+ public void aggregate(Tuple tuple, ImmutableBytesWritable ptr) {
+
+ //set pointer to ordering by field
+ children.get(1).evaluate(tuple, ptr);
+ byte[] currentOrder = ptr.copyBytes();
+
+ children.get(0).evaluate(tuple, ptr);
+
+ if (useOffset) {
+ if (topValues.size() < offset) {
+ try {
+ topValues.put(currentOrder,
ptr.copyBytes());
+ } catch (Exception e) {
+ logger.error(e.getMessage());
+ }
+ } else {
+ boolean add = false;
+ if (isAscending) {
+ byte[] lowestKey = topValues.lastKey();
+ if (Bytes.compareTo(currentOrder,
lowestKey) < 0) {
+ topValues.remove(lowestKey);
+ add = true;
+ }
+ } else { //desc
+ byte[] highestKey =
topValues.firstKey();
+ if (Bytes.compareTo(currentOrder,
highestKey) > 0) {
+ topValues.remove(highestKey);
+ add = true;
+ }
+ }
+
+ if (add) {
+ topValues.put(currentOrder,
ptr.copyBytes());
+ }
+ }
+ } else {
+ boolean isHigher;
+ if (isAscending) {
+ isHigher = topOrder.compareTo(currentOrder) > 0;
+ } else {
+ isHigher = topOrder.compareTo(currentOrder) <
0;//desc
+ }
+ if (topOrder.getValue().length < 1 || isHigher) {
+
+ topValue = ptr.copyBytes();
+ topOrder = new BinaryComparator(currentOrder);
+ }
+ }
+
+ }
+
+ @Override
+ public String toString() {
+ StringBuilder out = new
StringBuilder("FirstLastValueServerAggregator"
+ + " is ascending: " + isAscending + " value=");
+ if (useOffset) {
+ for (byte[] key : topValues.keySet()) {
+ out.append(topValues.get(key));
+ }
+ out.append(" offset = ").append(offset);
+ } else {
+ out.append(topValue);
+ }
+
+ return out.toString();
+ }
+
+ @Override
+ public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
+
+ if (useOffset) {
+ if (topValues.size() == 0) {
+ return false;
+ }
+
+ FirstLastValueOffsetDataContainer payload = new
FirstLastValueOffsetDataContainer();
+ payload.setIsAscending(isAscending);
+ payload.setOffset(offset);
+ payload.setData(topValues);
+
+ try {
+ ptr.set(payload.getPayload());
+ } catch (IOException ex) {
+ logger.error(ex.getMessage());
+ return false;
+ }
+ return true;
+ }
+
+ if (topValue == null) {
+ return false;
+ }
+
+ FirstLastValueDataContainer payload = new
FirstLastValueDataContainer();
+ payload.setOrdertValue(topOrder.getValue());
+ payload.setValue(topValue);
+ payload.setIsAscending(isAscending);
+
+ ptr.set(payload.getBytesMessage());
+ return true;
+ }
+
+ @Override
+ public PDataType getDataType() {
+ return PDataType.VARBINARY;
+ }
+
+ public void init(List<Expression> children, boolean isAscending, int
offset) {
+ this.children = children;
+ this.offset = offset;
+ if (offset > 0) {
+ useOffset = true;
+ }
+
+ //set order if modified
+ if (children.get(1).getSortOrder() == SortOrder.DESC) {
--- End diff --
Any test case for the sort order DESC? Is it supported in patch.?
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