/*
* 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.ignite.cache.query.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Annotates public static methods in classes to be used in SQL queries as custom functions.
* Annotated class must be registered in H2 indexing SPI using following method
* {@link org.apache.ignite.configuration.CacheConfiguration#setSqlFunctionClasses(Class[])}.
* <p>
* Example usage:
* <pre name="code" class="java">
* public class MyFunctions {
* @QuerySqlFunction
* public static int sqr(int x) {
* return x * x;
* }
* }
*
* // Register.
* indexing.setSqlFunctionClasses(MyFunctions.class);
*
* // And use in queries.
* cache.queries().createSqlFieldsQuery("select sqr(2) where sqr(1) = 1");
* </pre>
* <p>
* For more information about H2 custom functions please refer to
* <a href="http://www.h2database.com/html/features.html#user_defined_functions">H2 documentation</a>.
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface QuerySqlFunction {
/**
* Specifies alias for the function to be used form SQL queries.
* If no alias provided method name will be used.
*
* @return Alias for function.
*/
String alias() default "";
/**
* Specifies if the function is deterministic (result depends only on input parameters).
* <p>
* Deterministic function is a function which always returns the same result
* assuming that input parameters are the same.
*
* @return {@code true} If function is deterministic, {@code false} otherwise.
*/
boolean deterministic() default false;
}