io.druid.server.lookup.jdbc

Class JdbcDataFetcher

java.lang.Object

io.druid.server.lookup.jdbc.JdbcDataFetcher

All Implemented Interfaces:

DataFetcher<String,String>

public class JdbcDataFetcher
extends Object
implements DataFetcher<String,String>

Constructor Summary

Constructors

Constructor and Description
JdbcDataFetcher(MetadataStorageConnectorConfig connectorConfig, String table, String keyColumn, String valueColumn, Integer streamingFetchSize)

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
Iterable<Map.Entry<String,String>>	fetch(Iterable<String> keys) Function used to perform a bulk lookup
String	fetch(String key) Function to perform a one item lookup.
Iterable<Map.Entry<String,String>>	fetchAll() Function used to fetch all the pair of key-values from the lookup One use case of this method is to populate a polling cache PollingCache
List<String>	reverseFetchKeys(String value) Function used to perform reverse lookup
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

JdbcDataFetcher

public JdbcDataFetcher(MetadataStorageConnectorConfig connectorConfig,
                       String table,
                       String keyColumn,
                       String valueColumn,
                       Integer streamingFetchSize)

Method Detail

fetchAll

public Iterable<Map.Entry<String,String>> fetchAll()

Description copied from interface: DataFetcher

Function used to fetch all the pair of key-values from the lookup One use case of this method is to populate a polling cache PollingCache

Specified by:

fetchAll in interface DataFetcher<String,String>

Returns:

Returns an Iterable of key-value pairs.

fetch

public String fetch(String key)

Description copied from interface: DataFetcher

Function to perform a one item lookup. For instance this can be used by a loading cache to fetch the value in case of the cache doesn't have it

Specified by:

fetch in interface DataFetcher<String,String>

Parameters:

key - non-null key used to lookup the value

Returns:

Returns null if the key doesn't have an associated value, or the value if it exists

fetch

public Iterable<Map.Entry<String,String>> fetch(Iterable<String> keys)

Description copied from interface: DataFetcher

Function used to perform a bulk lookup

Specified by:

fetch in interface DataFetcher<String,String>

Parameters:

keys - used to lookup the respective values

Returns:

Returns a Iterable containing the pair of existing key-value.

reverseFetchKeys

public List<String> reverseFetchKeys(String value)

Description copied from interface: DataFetcher

Function used to perform reverse lookup

Specified by:

reverseFetchKeys in interface DataFetcher<String,String>

Parameters:

value - use to fetch it's keys from the lookup table

Returns:

Returns a list of keys of the given value or an empty list Collections.EmptyList

equals

public boolean equals(Object o)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object