com.datastax.driver.core

Interface ResultSet

All Superinterfaces:

Iterable<Row>, PagingIterable<ResultSet,Row>

public interface ResultSet
extends PagingIterable<ResultSet,Row>

The result of a query.

The retrieval of the rows of a ResultSet is generally paged (a first page of result is fetched and the next one is only fetched once all the results of the first one has been consumed). The size of the pages can be configured either globally through QueryOptions.setFetchSize(int) or per-statement with Statement.setFetchSize(int). Though new pages are automatically (and transparently) fetched when needed, it is possible to force the retrieval of the next page early through PagingIterable.fetchMoreResults(). Please note however that this ResultSet paging is not available with the version 1 of the native protocol (i.e. with Cassandra 1.2 or if version 1 has been explicitly requested through Cluster.Builder.withProtocolVersion(com.datastax.driver.core.ProtocolVersion)). If the protocol version 1 is in use, a ResultSet is always fetched in it's entirely and it's up to the client to make sure that no query can yield ResultSet that won't hold in memory.

Note that this class is not thread-safe.

Method Summary

Modifier and Type	Method and Description
ColumnDefinitions	getColumnDefinitions() Returns the columns returned in this ResultSet.
Row	one() Returns the next result from this result set.
boolean	wasApplied() If the query that produced this ResultSet was a conditional update, return whether it was successfully applied.

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

all, fetchMoreResults, getAllExecutionInfo, getAvailableWithoutFetching, getExecutionInfo, isExhausted, isFullyFetched, iterator

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

one

Row one()

Description copied from interface: PagingIterable

Returns the next result from this result set.

Specified by:

one in interface PagingIterable<ResultSet,Row>

Returns:

the next row in this result set or null if this result set is exhausted.

getColumnDefinitions

ColumnDefinitions getColumnDefinitions()

Returns the columns returned in this ResultSet.

Returns:

the columns returned in this ResultSet.

wasApplied

boolean wasApplied()

If the query that produced this ResultSet was a conditional update, return whether it was successfully applied.

This is equivalent to calling:

 rs.one().getBool("[applied]");
 

Except that this method peeks at the next row without consuming it.

For consistency, this method always returns true for non-conditional queries (although there is no reason to call the method in that case). This is also the case for conditional DDL statements (CREATE KEYSPACE... IF NOT EXISTS, CREATE TABLE... IF NOT EXISTS), for which Cassandra doesn't return an [applied] column.

Note that, for versions of Cassandra strictly lower than 2.0.9 and 2.1.0-rc2, a server-side bug (CASSANDRA-7337) causes this method to always return true for batches containing conditional queries.

Returns:

if the query was a conditional update, whether it was applied. true for other types of queries.

See Also:

CASSANDRA-7337