DowngradingConsistencyRetryPolicy Archives

Cassandra production scenarios/issues

This entry was posted in Cassandra and tagged ConstantReconnectionPolicy DCAwareRoundRobinPolicy DefaultRetryPolicy distributed calls in cassandra JDBC DowngradingConsistencyRetryPolicy ExponentialReconnectionPolicy Load Balancing Policy Read Reconnection Policy RetryPolicy RoundRobinPolicy TokenAwarePolicy Unavailable Write on January 28, 2016 by Siva

Production issue: when we are trying to write a select query with 8 lacks ids “in condition “. then we got faced below issue, To solve the above exception, we used distributed calls in Java client as shown below,


import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.ResultSetFuture;
import com.datastax.driver.core.Row;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.exceptions.NoHostAvailableException;

public class SelectCassandraDistrbuted {

public static void main(String[] args) {
		Cluster	 cluster = null;
		try{
	cluster = Cluster.builder().addContactPoints("node1 address/IP","node2 address/IP","node3 address/IP").build();
	cluster.getConfiguration().getSocketOptions().setReadTimeoutMillis(600000000);
	Session session = cluster.connect("keyspace_name");
	System.out.println("connected");
	PreparedStatement statement = session.prepare("select * from table where tmp_time = ?");
	
	List<String> idsList = new ArrayList<String>();
	
	//Here we added 8 lacs ids to the idsList list
	
	List<ResultSetFuture> futures = new ArrayList<ResultSetFuture>();
			
	//Here we are executing the query.
			for (String id:idsList) {
			 ResultSetFuture resultSetFuture = session.executeAsync(statement.bind(id));
			 futures.add(resultSetFuture);
			}
	//Fetching the results
			for (ResultSetFuture future : futures){
			 ResultSet rows = future.getUninterruptibly();
			 Row row = rows.one();
			 System.out.println(row.getString("sys_serial_no"));
			 System.out.println(row.getString("tmp_time"));
			
			}
}

import java.net.InetSocketAddress;

import java.util.ArrayList;

import java.util.List;

import java.util.Map;

import com.datastax.driver.core.Cluster;

import com.datastax.driver.core.PreparedStatement;

import com.datastax.driver.core.ResultSet;

import com.datastax.driver.core.ResultSetFuture;

import com.datastax.driver.core.Row;

import com.datastax.driver.core.Session;

import com.datastax.driver.core.exceptions.NoHostAvailableException;

public class SelectCassandraDistrbuted {

public static void main(String[] args) {

Cluster cluster = null;

try{

cluster = Cluster.builder().addContactPoints("node1 address/IP","node2 address/IP","node3 address/IP").build();

cluster.getConfiguration().getSocketOptions().setReadTimeoutMillis(600000000);

Session session = cluster.connect("keyspace_name");

System.out.println("connected");

PreparedStatement statement = session.prepare("select * from table where tmp_time = ?");

List<String> idsList = new ArrayList<String>();

//Here we added 8 lacs ids to the idsList list

List<ResultSetFuture> futures = new ArrayList<ResultSetFuture>();

//Here we are executing the query.

for (String id:idsList) {

ResultSetFuture resultSetFuture = session.executeAsync(statement.bind(id));

futures.add(resultSetFuture);

}

//Fetching the results

for (ResultSetFuture future : futures){

ResultSet rows = future.getUninterruptibly();

Row row = rows.one();

System.out.println(row.getString("sys_serial_no"));

System.out.println(row.getString("tmp_time"));

}

Few Production configurations in cassandra RetryPolicy Three scenarios you can control retry policy for: Read time out: When a coordinator received the request and sent the read to replica(s) but the replica(s) […]