com.datastax.dse.driver.api.core.cql.continuous

Interface ContinuousResultSet

All Superinterfaces:

Iterable<Row>, PagingIterable<Row>, ResultSet

public interface ContinuousResultSet
extends ResultSet

The result of a synchronous continuous paging query.

It uses asynchronous calls internally, but blocks on the results in order to provide a synchronous API to its clients. If the query is paged, only the first page will be fetched initially, and iteration will trigger background fetches of the next pages when necessary.

Note that this object can only be iterated once: rows are "consumed" as they are read, subsequent calls to iterator() will return the same iterator instance.

Implementations of this type are not thread-safe. They can only be iterated by the thread that invoked session.executeContinuously.

Method Summary

Modifier and Type	Method and Description
void	cancel() Cancels the continuous query.
default ExecutionInfo	getExecutionInfo() The execution information for the last query performed for this iterable.

Methods inherited from interface com.datastax.oss.driver.api.core.cql.ResultSet

wasApplied

Methods inherited from interface com.datastax.oss.driver.api.core.PagingIterable

all, getAvailableWithoutFetching, getColumnDefinitions, getExecutionInfos, isFullyFetched, map, one, spliterator

Methods inherited from interface java.lang.Iterable

forEach, iterator

Method Detail

cancel

void cancel()

Cancels the continuous query.

There might still be rows available in the current page after the cancellation; the iteration will only stop when such rows are fully iterated upon.

Also, there might be more pages available in the driver's local page cache after the cancellation; these extra pages will be discarded.

Therefore, if you plan to resume the iteration later, the correct procedure is as follows:

1. Cancel the operation by invoking this method;
2. Keep iterating on this object until it doesn't return any more rows;
3. Retrieve the paging state with getExecutionInfo().getPagingState();
4. Re-inject the paging state in the statement;
5. Resume the operation by invoking executeContinuously again.

getExecutionInfo

@NonNull
default ExecutionInfo getExecutionInfo()

The execution information for the last query performed for this iterable.

This is a shortcut for:

 getExecutionInfos().get(getExecutionInfos().size() - 1)
 

Note: because the driver does not support query traces for continuous queries, ExecutionInfo.getTracingId() will always be null.

Specified by:

getExecutionInfo in interface PagingIterable<Row>

See Also:

PagingIterable.getExecutionInfos()