/*
* 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.jena.sdb.core.sqlnode;
import org.apache.jena.atlas.io.IndentedLineBuffer;
import org.apache.jena.atlas.io.IndentedWriter;
import org.apache.jena.sdb.core.JoinType ;
public class GenerateSQLMySQL extends GenerateSQL
{
@Override
protected SqlNodeVisitor makeVisitor(IndentedLineBuffer buff)
{
return new GeneratorVisitorMySQL(buff) ;
}
}
class GeneratorVisitorMySQL extends GenerateSQLVisitor
{
// STRAIGHT_JOIN stops the optimizer reordering inner join
// It requires that the left table and right table are kept as left and right,
// so a sequence of joins can not be reordered.
static final String InnerJoinOperatorStraight = "STRAIGHT_JOIN" ;
static final String InnerJoinOperatorDefault = JoinType.INNER.sqlOperator() ;
public GeneratorVisitorMySQL(IndentedWriter out) { super(out) ; }
@Override
public void visit(SqlJoinInner join)
{
join = rewrite(join) ;
visitJoin(join, InnerJoinOperatorDefault) ;
}
@Override
protected void genLimitOffset(SqlSelectBlock sqlSelectBlock)
{
if ( sqlSelectBlock.getLength() >= 0 || sqlSelectBlock.getStart() >= 0 )
{
// MySQL syntax issue - need LIMIT even if only OFFSET
long length = sqlSelectBlock.getLength() ;
if ( length < 0 )
{
sqlSelectBlock.addNote("Require large LIMIT") ;
length = Long.MAX_VALUE ;
}
out.println("LIMIT "+length) ;
if ( sqlSelectBlock.getStart() >= 0 )
out.println("OFFSET "+sqlSelectBlock.getStart()) ;
}
}
}