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https://issues.apache.org/jira/browse/TAJO-1092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14169361#comment-14169361
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ASF GitHub Bot commented on TAJO-1092:
--------------------------------------
Github user jinossy commented on a diff in the pull request:
https://github.com/apache/tajo/pull/178#discussion_r18773411
--- Diff:
tajo-core/src/main/java/org/apache/tajo/engine/function/math/MathFunctions.java
---
@@ -0,0 +1,46 @@
+/***
+ * 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.tajo.engine.function.math;
+
+import org.apache.tajo.function.FunctionCollection;
+import org.apache.tajo.function.ScalarFunction;
+
+import static org.apache.tajo.common.TajoDataTypes.Type.FLOAT8;
+
+@FunctionCollection
+public class MathFunctions {
+
+ @ScalarFunction(name = "pi", returnType = FLOAT8)
+ public static double pi() {
+ return Math.PI;
+ }
+
+ @ScalarFunction(name = "pow", returnType = FLOAT8, paramTypes = {FLOAT8,
FLOAT8})
+ public static Double pow(Double x, Double y) {
+ if (x == null || y == null) {
+ return null;
+ }
+ return Math.pow(x, y);
+ }
+
+// @ScalarFunction(name = "pow", returnType = FLOAT8, paramTypes =
{FLOAT8, FLOAT8})
--- End diff --
Please remove the commented out line.
> Improve the function system to allow other function implementation types
> ------------------------------------------------------------------------
>
> Key: TAJO-1092
> URL: https://issues.apache.org/jira/browse/TAJO-1092
> Project: Tajo
> Issue Type: Improvement
> Components: function/udf
> Reporter: Hyunsik Choi
> Assignee: Hyunsik Choi
> Fix For: 0.9.1, block_iteration
>
>
> In the current function system, each function implementation is a single Java
> class subclassed from org.apache.tajo.catalog.function.Function.
> In this approach, there are many rooms for improvement. This approach always
> uses Datum as input and output values of functions, creating unnecessary
> objects. It does not likely to exploit given information included query
> statements; for example, some parameters are constants or variables.
> In this issue, I propose the improvement to allow the function system to
> support other function implementation types. In addition, I propose three
> function implementation types:
> - legacy Java class function provided by the current Tajo
> - static method in Java class
> - code generation by ASM
> Later, we could expand this feature to allow Pig or Hive functions in Tajo.
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