org.apache.druid.data.input.impl.prefetch

Class SqlFetcher<T>

java.lang.Object

org.apache.druid.data.input.impl.prefetch.Fetcher<T>

org.apache.druid.data.input.impl.prefetch.SqlFetcher<T>

All Implemented Interfaces:

Iterator<org.apache.druid.data.input.impl.prefetch.OpenedObject<T>>

public class SqlFetcher<T>
extends Fetcher<T>

A file fetcher used by PrefetchSqlFirehoseFactory. See the javadoc of PrefetchSqlFirehoseFactory for more details.

Method Summary

Modifier and Type	Method and Description
protected long	download(T object, File outFile) Downloads the entire resultset object into a file.
protected org.apache.druid.data.input.impl.prefetch.OpenedObject<T>	generateOpenObject(T object) Generates an instance of OpenedObject for the given object.

Methods inherited from class org.apache.druid.data.input.impl.prefetch.Fetcher

hasNext, next

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Method Detail

download

protected long download(T object,
                        File outFile)
                 throws IOException

Downloads the entire resultset object into a file. This avoids maintaining a persistent connection to the database. The retry is performed at the query execution layer.

Specified by:

download in class Fetcher<T>

Parameters:

object - sql query for which the resultset is to be downloaded

outFile - a file which the object data is stored

Returns:

size of downloaded resultset

Throws:

IOException

generateOpenObject

protected org.apache.druid.data.input.impl.prefetch.OpenedObject<T> generateOpenObject(T object)
                                                                                throws IOException

Generates an instance of OpenedObject for the given object. This is usually called when prefetching is disabled. The retry is performed at the query execution layer.

Specified by:

generateOpenObject in class Fetcher<T>

Throws:

IOException