SQLTypeInfo.java

/*
 * Copyright (c) 2010, Stanislav Muhametsin. All Rights Reserved.
 *
 * Licensed 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.qi4j.index.sql.support.api;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.math.BigDecimal;
import java.math.BigInteger;

/**
 * The annotation, which tells the parameters for SQL type. Only applyable to certain typed properties, like for now, {@link String}, {@link BigInteger}, and {@link BigDecimal}.
 *
 * Example of usage, where we want to limit the datatype of column storing this value in RDBMS to be 100 characters of max length:
 * <pre>@SQLTypeInfo(maxLength=100)
 * public Property<String> myStringProperty();</pre>
 *
 * The purpose of this class is to optimize performance for people who know for certain that they will be using SQL-Indexing in their application.
 *
 * @author Stanislav Muhametsin
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface SQLTypeInfo
{
   /**
    * For {@link String}s, this is the max character length as specified by {@code VARCHAR(length)}. For {@link BigInteger}s and {@link BigDecimal}s,
    * this is the precision of a {@code NUMERIC}.
    * @return Maximum length for SQL data type representing some property type.
    */
   int maxLength();

   /**
    * For {@link String}s and {@link BigInteger}s, this value is ignored. For {@link BigDecimal}s, this is the scale of {@code NUMERIC}, default being {@code 50}.
    *
    * @return The scale of SQL data type representing some property type.
    */
   int scale() default 50;
}