/*
* 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.easycassandra.persistence.cassandra;
import org.easycassandra.ClassInformation;
import org.easycassandra.ClassInformation.KeySpaceInformation;
import org.easycassandra.ClassInformations;
import com.datastax.driver.core.ConsistencyLevel;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.querybuilder.QueryBuilder;
import com.datastax.driver.core.querybuilder.Select;
/**
* Class to mount and execute a query to return the number of column in a family
* column.
* @author otaviojava
*/
class CountQuery {
private String keySpace;
public CountQuery(String keySpace) {
this.keySpace = keySpace;
}
/**
* return the number of row in a column family.
* @param bean - column family
* @param session
* @return number of register in a column family
*/
public Long count(Class<?> bean, Session session,
ConsistencyLevel consistency) {
Select select = prepareCount(bean, consistency);
ResultSet resultSet = session.execute(select);
return resultSet.all().get(0).getLong(0);
}
protected Select prepareCount(Class<?> bean, ConsistencyLevel consistency) {
ClassInformation classInformation = ClassInformations.INSTACE.getClass(bean);
KeySpaceInformation key = classInformation.getKeySpace(keySpace);
Select select = QueryBuilder.select().countAll()
.from(key.getKeySpace(), key.getColumnFamily());
select.setConsistencyLevel(consistency);
return select;
}
}