org.apache.drill.exec.physical.resultSet.impl

Class PullResultSetReaderImpl

java.lang.Object

org.apache.drill.exec.physical.resultSet.impl.PullResultSetReaderImpl

All Implemented Interfaces:

PullResultSetReader

public class PullResultSetReaderImpl
extends Object
implements PullResultSetReader

Protocol

1. Create an instance, passing in a PullResultSetReaderImpl.UpstreamSource to provide batches and optional selection vector.
2. For each incoming batch:
   1. Call #start() to attach the batch. The associated BatchAccessor reports if the schema has changed.
   2. Call reader() to obtain a reader.
   3. Iterate over the batch using the reader.
   4. Call #release() to free the memory for the incoming batch. Or, to call #detach() to keep the batch memory.
3. Call close() after all batches are read.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	PullResultSetReaderImpl.State
static interface	PullResultSetReaderImpl.UpstreamSource

Constructor Summary

Constructors

Constructor and Description
PullResultSetReaderImpl(PullResultSetReaderImpl.UpstreamSource source)

Method Summary

Modifier and Type	Method and Description
void	close() Close this reader.
boolean	next() Advance to the next batch of data.
RowSetReader	reader() Obtain a reader to iterate over the rows of the batch.
TupleMetadata	schema() Return the schema for this result set.
int	schemaVersion()
protected PullResultSetReaderImpl.State	state()

Methods inherited from class java.lang.Object

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

Constructor Detail

PullResultSetReaderImpl

public PullResultSetReaderImpl(PullResultSetReaderImpl.UpstreamSource source)

Method Detail

schema

public TupleMetadata schema()

Description copied from interface: PullResultSetReader

Return the schema for this result set.

Specified by:

schema in interface PullResultSetReader

next

public boolean next()

Description copied from interface: PullResultSetReader

Advance to the next batch of data. The iterator starts positioned before the first batch (but after obtaining a schema.)

Specified by:

next in interface PullResultSetReader

Returns:

true if another batch is available, false if EOF

schemaVersion

public int schemaVersion()

Specified by:

schemaVersion in interface PullResultSetReader

reader

public RowSetReader reader()

Description copied from interface: PullResultSetReader

Obtain a reader to iterate over the rows of the batch. The return value will likely be the same reader each time, so that this call is optional after the first batch.

Specified by:

reader in interface PullResultSetReader

close

public void close()

Description copied from interface: PullResultSetReader

Close this reader. Releases any memory still assigned to any attached batch. Call #detach() first if you want to preserve the batch memory.

Specified by:

close in interface PullResultSetReader

state

protected PullResultSetReaderImpl.State state()