com.datastax.driver.core

Class QueryTrace

java.lang.Object

com.datastax.driver.core.QueryTrace

public class QueryTrace
extends Object

The Cassandra trace for a query.

A trace is generated by Cassandra when query tracing is enabled for the query. The trace itself is stored in Cassandra in the sessions and events table in the system_traces keyspace and can be retrieve manually using the trace identifier (the one returned by getTraceId()).

This class provides facilities to fetch the traces from Cassandra. Please note that the writing of the trace is done asynchronously in Cassandra. So accessing the trace too soon after the query may result in the trace being incomplete.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	QueryTrace.Event A trace event.

Method Summary

Modifier and Type	Method and Description
InetAddress	getCoordinator() Returns the coordinator host of the query.
int	getDurationMicros() Returns the server-side duration of the query in microseconds.
List<QueryTrace.Event>	getEvents() Returns the events contained in this trace.
Map<String,String>	getParameters() Returns the parameters attached to this trace.
String	getRequestType() Returns the type of request.
long	getStartedAt() Returns the server-side timestamp of the start of this query.
UUID	getTraceId() Returns the identifier of this trace.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getTraceId

public UUID getTraceId()

Returns the identifier of this trace.

Note that contrary to the other methods in this class, this does not entail fetching query trace details from Cassandra.

Returns:

the identifier of this trace.

getRequestType

public String getRequestType()

Returns the type of request.

Returns:

the type of request or null if the request type is not yet available.

Throws:

TraceRetrievalException - if the trace details cannot be retrieve from Cassandra successfully.

getDurationMicros

public int getDurationMicros()

Returns the server-side duration of the query in microseconds.

Returns:

the (server side) duration of the query in microseconds. This method will return Integer.MIN_VALUE if the duration is not yet available.

Throws:

TraceRetrievalException - if the trace details cannot be retrieve from Cassandra successfully.

getCoordinator

public InetAddress getCoordinator()

Returns the coordinator host of the query.

Returns:

the coordinator host of the query or null if the coordinator is not yet available.

Throws:

TraceRetrievalException - if the trace details cannot be retrieve from Cassandra successfully.

getParameters

public Map<String,String> getParameters()

Returns the parameters attached to this trace.

Returns:

the parameters attached to this trace. or null if the coordinator is not yet available.

Throws:

TraceRetrievalException - if the trace details cannot be retrieve from Cassandra successfully.

getStartedAt

public long getStartedAt()

Returns the server-side timestamp of the start of this query.

Returns:

the server side timestamp of the start of this query or 0 if the start timestamp is not available.

Throws:

TraceRetrievalException - if the trace details cannot be retrieve from Cassandra successfully.

getEvents

public List<QueryTrace.Event> getEvents()

Returns the events contained in this trace.

Query tracing is asynchronous in Cassandra. Hence, it is possible for the list returned to be missing some events for some of the replica involved in the query if the query trace is requested just after the return of the query it is a trace of (the only guarantee being that the list will contain the events pertaining to the coordinator of the query).

Returns:

the events contained in this trace.

Throws:

TraceRetrievalException - if the trace details cannot be retrieve from Cassandra successfully.

toString

public String toString()

Overrides:

toString in class Object