Package org.apache.druid.sql.avatica

Class DruidJdbcResultSet

java.lang.Object

org.apache.druid.sql.avatica.DruidJdbcResultSet

All Implemented Interfaces:

Closeable, AutoCloseable

public class DruidJdbcResultSet
extends Object
implements Closeable

Druid's server-side representation of a JDBC result set. At most one can be open per statement (standard or prepared). The implementation is based on Druid's own DirectStatement class. Even if result set is for a PreparedStatement, the result set itself uses a Druid DirectStatement which includes the parameter values given for the execution. This allows Druid's planner to use the "query optimized" form of parameter substitution: we replan the query for each execution with the parameter values.

Avatica returns results in Meta.Frame objects as batches of rows. The result set uses the TYPE_FORWARD_ONLY execution model: the application can only read results sequentially, the application can't jump around or read backwards. As a result, the enclosing statement closes the result set at EOF to release resources early.

Thread safe, but only when accessed sequentially by different request threads: not designed for concurrent access as JDBC does not support concurrent actions on the same result set.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	DruidJdbcResultSet.ResultFetcher	Asynchronous result fetcher.
static class	DruidJdbcResultSet.ResultFetcherFactory	Creates the result fetcher and holds config.

Constructor Summary

Constructors

Constructor	Description
DruidJdbcResultSet(AbstractDruidJdbcStatement jdbcStatement, DirectStatement stmt, long maxRowCount, DruidJdbcResultSet.ResultFetcherFactory fetcherFactory)

Method Summary

Modifier and Type	Method	Description
void	close()
void	execute()
long	getCurrentOffset()
org.apache.calcite.avatica.Meta.Signature	getSignature()
boolean	isDone()
org.apache.calcite.avatica.Meta.Frame	nextFrame(long fetchOffset, int fetchMaxRowCount)

Methods inherited from class java.lang.Object

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

Constructor Details

DruidJdbcResultSet

public DruidJdbcResultSet(AbstractDruidJdbcStatement jdbcStatement,
 DirectStatement stmt,
 long maxRowCount,
 DruidJdbcResultSet.ResultFetcherFactory fetcherFactory)

Method Details

execute

public void execute()

isDone

public boolean isDone()

getSignature

public org.apache.calcite.avatica.Meta.Signature getSignature()

nextFrame

public org.apache.calcite.avatica.Meta.Frame nextFrame(long fetchOffset,
 int fetchMaxRowCount)

getCurrentOffset

public long getCurrentOffset()

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable