com.blazebit.persistence.impl.dialect.OracleDbmsLimitHandler 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.impl.util.BoyerMooreCaseInsensitiveAsciiLastPatternFinder;
import com.blazebit.persistence.impl.util.PatternFinder;
import com.blazebit.persistence.impl.util.SqlUtils;
import java.sql.PreparedStatement;
import java.sql.SQLException;
/**
* @author Christian Beikov
* @since 1.2.0
*/
public class OracleDbmsLimitHandler extends AbstractDbmsLimitHandler {
private static final PatternFinder FOR_UPDATE_FINDER = new BoyerMooreCaseInsensitiveAsciiLastPatternFinder("for update");
public OracleDbmsLimitHandler() {
super(40);
}
public OracleDbmsLimitHandler(int length) {
super(length);
}
@Override
public boolean supportsVariableLimit() {
return true;
}
@Override
public boolean limitIncludesOffset() {
return true;
}
@Override
public void applySql(StringBuilder sqlSb, boolean isSubquery, String limit, String offset) {
int selectIndex = SqlUtils.indexOfSelect(sqlSb);
if (offset != null) {
if (limit != null) {
// Need to extract aliases and place them in the outer select so we don't screw up subqueries
String[] aliases = SqlUtils.getSelectItemAliases(sqlSb, selectIndex);
StringBuilder selectClauseSb = new StringBuilder(60 + aliases.length * 20);
selectClauseSb.append("select ");
for (int i = 0; i < aliases.length; i++) {
selectClauseSb.append(aliases[i]);
selectClauseSb.append(',');
}
selectClauseSb.setCharAt(selectClauseSb.length() - 1, ' ');
selectClauseSb.append("from ( select row_.*, rownum rownum_ from ( ");
// We know we will need some more
sqlSb.ensureCapacity(sqlSb.length() + 50 + selectClauseSb.length());
sqlSb.insert(selectIndex, selectClauseSb);
} else {
sqlSb.ensureCapacity(sqlSb.length() + 50);
sqlSb.insert(selectIndex, "select * from ( ");
}
} else {
sqlSb.ensureCapacity(sqlSb.length() + 50);
sqlSb.insert(selectIndex, "select * from ( ");
}
// The FOR UPDATE clause must be the last, so we find the index at which we should insert
int forUpdateIndex = FOR_UPDATE_FINDER.indexIn(sqlSb);
forUpdateIndex = forUpdateIndex == -1 ? sqlSb.length() : forUpdateIndex - 1;
if (offset != null) {
if (limit != null) {
sqlSb.insert(forUpdateIndex, " ) row_ where rownum <= " + (Integer.parseInt(limit) + Integer.parseInt(offset)) + ") where rownum_ > " + offset);
} else {
sqlSb.insert(forUpdateIndex, " ) where rownum > " + offset);
}
} else {
sqlSb.insert(forUpdateIndex, " ) where rownum <= " + limit);
}
}
@Override
public int bindLimitParametersAtEndOfQuery(Integer limit, Integer offset, PreparedStatement statement, int index) throws SQLException {
if (offset != null) {
if (limit != null) {
statement.setInt(index, limit + offset);
statement.setInt(index + 1, offset);
return 2;
} else {
statement.setInt(index, offset);
return 1;
}
} else if (limit != null) {
statement.setInt(index, limit);
return 1;
}
return 0;
}
}