com.blazebit.persistence.impl.dialect.MySQLDbmsDialect Maven / Gradle / Ivy
/*
* Copyright 2014 - 2020 Blazebit.
*
* 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 com.blazebit.persistence.impl.dialect;
import com.blazebit.persistence.spi.DbmsLimitHandler;
import com.blazebit.persistence.spi.LateralStyle;
import com.blazebit.persistence.spi.OrderByElement;
import com.blazebit.persistence.spi.ValuesStrategy;
import java.util.HashMap;
import java.util.Map;
/**
*
* @author Christian Beikov
* @author Moritz Becker
* @since 1.0.0
*/
public class MySQLDbmsDialect extends DefaultDbmsDialect {
public MySQLDbmsDialect() {
super(getSqlTypes());
}
public MySQLDbmsDialect(Map, String> childSqlTypes) {
super(childSqlTypes);
}
protected static Map, String> getSqlTypes() {
Map, String> types = new HashMap, String>();
types.put(String.class, "longtext");
return types;
}
@Override
public boolean supportsWindowFunctions() {
return false;
}
@Override
public boolean supportsWithClause() {
return false;
}
@Override
public boolean supportsNonRecursiveWithClause() {
return false;
}
@Override
public boolean isNullSmallest() {
return true;
}
@Override
public boolean requiresNullCast() {
return false;
}
@Override
public LateralStyle getLateralStyle() {
return LateralStyle.NONE;
}
@Override
public boolean supportsArbitraryLengthMultiset() {
return true;
}
@Override
public String getDummyTable() {
return "dual";
}
@Override
public String getWithClause(boolean recursive) {
throw new UnsupportedOperationException("With clause is not supported!");
}
@Override
public boolean supportsUnion(boolean all) {
return true;
}
@Override
public boolean supportsIntersect(boolean all) {
return false;
}
@Override
public boolean supportsExcept(boolean all) {
return false;
}
@Override
public boolean supportsGroupByExpressionInHavingMatching() {
// MySQL re-evaluates all expressions in the having clause which is why it needs access to all column values
return false;
}
@Override
public boolean supportsFullRowValueComparison() {
// MySQL can correctly evaluate row value comparisons but only uses them as filter predicate when accessing the index.
// http://use-the-index-luke.com/de/sql/partielle-ergebnisse/blaettern
return true;
}
@Override
public DbmsLimitHandler createLimitHandler() {
return new MySQLDbmsLimitHandler();
}
@Override
public void appendOrderByElement(StringBuilder sqlSb, OrderByElement element, String[] aliases) {
if (!element.isNullable()) {
super.appendOrderByElement(sqlSb, element, aliases);
} else {
appendEmulatedOrderByElementWithNulls(sqlSb, element, aliases);
}
}
@Override
public ValuesStrategy getValuesStrategy() {
return ValuesStrategy.SELECT_UNION;
}
@Override
public boolean needsCastParameters() {
return false;
}
@Override
protected boolean needsAliasForFromClause() {
return true;
}
@Override
public boolean supportsNullPrecedence() {
return false;
}
}