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https://issues.apache.org/jira/browse/PHOENIX-1715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14360734#comment-14360734
]
ASF GitHub Bot commented on PHOENIX-1715:
-----------------------------------------
Github user JamesRTaylor commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/45#discussion_r26406807
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/expression/function/SignFunction.java
---
@@ -0,0 +1,71 @@
+/*
+ * 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.function;
+
+import java.sql.SQLException;
+import java.util.List;
+
+import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
+import org.apache.phoenix.expression.Expression;
+import org.apache.phoenix.parse.FunctionParseNode.Argument;
+import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
+import org.apache.phoenix.schema.tuple.Tuple;
+import org.apache.phoenix.schema.types.PDataType;
+import org.apache.phoenix.schema.types.PInteger;
+import org.apache.phoenix.schema.types.PNumericType;
+
+/**
+ * Base class for built-in SIGN function.
+ * @since 4.3.0
+ */
+@BuiltInFunction(name = SignFunction.NAME,
+ args = { @Argument(allowedTypes = { PNumericType.class }) })
+public class SignFunction extends ScalarFunction {
+
+ public static final String NAME = "SIGN";
+
+ public SignFunction() {
+ }
+
+ public SignFunction(List<Expression> children) throws SQLException {
+ super(children);
+ }
+
+ @Override
+ public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
+ Expression childExpr = children.get(0);
+ PDataType dataType = childExpr.getDataType();
+ if (childExpr.evaluate(tuple, ptr)) {
+ int ret = ((PNumericType) dataType).signum(ptr,
childExpr.getSortOrder());
+ byte[] retBytes =
PInteger.INSTANCE.toBytes(Integer.valueOf(ret));
--- End diff --
Can you restore back the way you did an RESULT[ret] to get the bytes of the
return value here please?
> Implement Build-in math function Sign
> -------------------------------------
>
> Key: PHOENIX-1715
> URL: https://issues.apache.org/jira/browse/PHOENIX-1715
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Shuxiong Ye
> Assignee: Shuxiong Ye
>
> Take a look at the typical math functions that are implemented in relational
> database systems
> (http://www.postgresql.org/docs/current/static/functions-math.html) and
> implement the same for Phoenix in Java following this guide:
> http://phoenix-hbase.blogspot.com/2013/04/how-to-add-your-own-built-in-function.html
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