package test1;
import java.util.Date;
import com.datastax.driver.core.*;
import com.datastax.driver.core.policies.DCAwareRoundRobinPolicy;
/*
* Simple Java client test to connect to trial cluster, create a time series data table, fill it, query it, and save it as csv for graphing.
*/
public class CassTest1 {
// the 3 node trial Cassandra test cluster Public IPs. These are dummy values.
static String n1PubIP = "01.23.45.678";
static String n2PubIP = "01.234.56.78";
static String n3PubIP = "01.23.456.78";
static String dcName = "hal_sydney"; // this is the DC name you used when created
static String user = "user";
static String password = "password";
public static void main(String[] args) {
long t1 = 0; // time each CQL operation, t1 is start time t2 is end time, time is t2-t1
long t2 = 0;
long time = 0;
Cluster.Builder clusterBuilder = Cluster.builder()
.addContactPoints(
n1PubIP, n2PubIP, n3PubIP // provide all 3 public IPs
)
.withLoadBalancingPolicy(DCAwareRoundRobinPolicy.builder().withLocalDc(dcName).build()) // your local data centre
.withPort(9042)
.withAuthProvider(new PlainTextAuthProvider(user, password));
Cluster cluster = null;
try {
cluster = clusterBuilder.build();
Metadata metadata = cluster.getMetadata();
System.out.printf("Connected to cluster: %s\n", metadata.getClusterName());
for (Host host: metadata.getAllHosts()) {
System.out.printf("Datacenter: %s; Host: %s; Rack: %s\n", host.getDatacenter(), host.getAddress(), host.getRack());
}
Session session = cluster.connect();
ResultSet rs;
boolean createTable = true;
if (createTable) {
rs = session.execute("CREATE KEYSPACE IF NOT EXISTS hals WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 3}");
rs = session.execute("DROP TABLE IF EXISTS hals.sensordata");
rs = session.execute("CREATE TABLE hals.sensordata(host text, metric text, time timestamp, value double, PRIMARY KEY ((host, metric), time) ) WITH CLUSTERING ORDER BY (time ASC)");
System.out.println("Table hals.sensordata created!");
}
// Fill the table with some realistic sensor data. if createTable=false we just ADD data to the table
double startValue = 100; // start value for random walk
double nextValue = startValue; // next value in random walk, initially startValue
int numHosts = 100; // how many host names to generate
int toCreate = 1000; // how many times to pick a host name and create all metrics for it
boolean usePrepared = false;
PreparedStatement prepared = null;
// prepare a prepared statement
if (usePrepared)
{
System.out.println("Using PREPARED statements for INSERT");
prepared = session.prepare("insert into hals.sensordata (host, metric, time, value) values (?, ?, ?, ?)");
}
t1 = System.currentTimeMillis();
System.out.println("Creating data... iterations = " + toCreate);
for (int r=1; r <= toCreate; r++) {
long now = System.currentTimeMillis();
Date date = new Date(now);
// generate a random host name
String hostname = "host" + (long)Math.round((Math.random() * numHosts));
// do a random walk to produce realistic data
double rand = Math.random();
if (rand < 0.5)
// 50% chance that value doesn't change
;
else if (rand < 0.75)
// 25% chance that value increases by 1
nextValue++;
else
// 25% chance that value decreases by 1
nextValue--;
// never go negative
if (nextValue < 0)
nextValue = 0;
// comparison of prepared vs. non-prepared statements
if (usePrepared) {
session.execute(prepared.bind("'" + hostname + "'", "'m1'", date, nextValue));
session.execute(prepared.bind("'" + hostname + "'", "'m2'", date, nextValue * 10));
session.execute(prepared.bind("'" + hostname + "'", "'m3'", date, nextValue * 100));
}
else {
// fake three metrics (m1, m2, m3) which are somehow related.
rs = session.execute("insert into hals.sensordata (host, metric, time, value) values (" + "'" + hostname + "'" + ", " + "'m1'" + ", " + now + "," + (nextValue) + ");" );
rs = session.execute("insert into hals.sensordata (host, metric, time, value) values (" + "'" + hostname + "'" + ", " + "'m2'" + ", " + now + "," + (nextValue * 10) + ");" );
rs = session.execute("insert into hals.sensordata (host, metric, time, value) values (" + "'" + hostname + "'" + ", " + "'m3'" + ", " + now + "," + (nextValue * 100) + ");" );
}
}
t2 = System.currentTimeMillis();
System.out.println("Created rows = " + toCreate*3 + " in time = " + (t2-t1));
// find the max value for a sample
System.out.println("Getting max value for sample...");
t1 = System.currentTimeMillis();
rs = session.execute("select max(value) from hals.sensordata where host='host1' and metric='m1'");
t2 = System.currentTimeMillis();
time = t2-t1;
Row row = rs.one();
System.out.println("Max value = " + row.toString() + " in time = " + time);
// get all the values for a sample
System.out.println("Getting all rows for sample...");
t1 = System.currentTimeMillis();
rs = session.execute("select * from hals.sensordata where host='host1' and metric='m1'");
for (Row rowN : rs) {
System.out.println(rowN.toString());
}
t2 = System.currentTimeMillis();
time = t2-t1;
System.out.println("time = " + time);
// get all host/metric permutations
System.out.println("Getting all host/metric permutations");
t1 = System.currentTimeMillis();
rs = session.execute("select distinct host, metric from hals.sensordata");
for (Row rowN : rs) {
System.out.println(rowN.toString());
}
t2 = System.currentTimeMillis();
time = t2-t1;
System.out.println("time = " + time);
// Note that SELECT * will return all results without limit (even though the driver might use multiple queries in the background).
// To handle large result sets, you use a LIMIT clause in your CQL query, or use one of the techniques described in the paging documentation.
System.out.println("Select ALL...");
t1 = System.currentTimeMillis();
rs = session.execute("select * from hals.sensordata");
System.out.println("Got rows (without fetching) = " + rs.getAvailableWithoutFetching());
int i = 0;
long numBytes = 0;
// example use of the data: count rows and total bytes returned.
for (Row rowN : rs)
{
i++;
numBytes += rowN.toString().length();
}
t2 = System.currentTimeMillis();
time = t2-t1;
System.out.println("Returned rows = " + i + ", total bytes = " + numBytes + ", in time = " + time);
} finally {
if (cluster != null) cluster.close();
}
}
}
