BetterHSQLDialect.java

/*
 * Copyright 2025 Global Crop Diversity Trust
 *
 * 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.genesys.blocks.util;

import org.hibernate.boot.model.FunctionContributions;
import org.hibernate.dialect.HSQLDialect;
import org.hibernate.dialect.function.CommonFunctionFactory;

/**
 * Hibernate's HSQL dialect uses clob(255) when length is not specified.
 *
 * Example: For JDBC connection to
 * <code>jdbc:hsqldb:mem:catalog;sql.syntax_mys=true;sql.ignore_case=true</code>
 * set Hibernate dialect to
 * <code>org.genesys.blocks.util.BetterHSQLDialect</code>.
 */
public class BetterHSQLDialect extends HSQLDialect {

	@Override
	protected void registerDefaultKeywords() {
		super.registerDefaultKeywords();
		// Needed for OFFSET 0 ROWS FETCH FIRST 1 ROWS ONLY
		registerKeyword("OFFSET");
		registerKeyword("FETCH");
		registerKeyword("FIRST");
		registerKeyword("ROWS");
		registerKeyword("ONLY");
		registerKeyword("day"); // Needed for DATEDIFF(DAY, ...)
	}

	@Override
	public void initializeFunctionRegistry(FunctionContributions functionContributions) {
		super.initializeFunctionRegistry(functionContributions);
		CommonFunctionFactory functionFactory = new CommonFunctionFactory(functionContributions);
		functionFactory.datediff();
		functionFactory.stddev();

	}
}