Package org.apache.druid.client.selector

Class PooledTierSelectorStrategy

java.lang.Object

org.apache.druid.client.selector.AbstractTierSelectorStrategy

org.apache.druid.client.selector.PooledTierSelectorStrategy

All Implemented Interfaces:

TierSelectorStrategy

public class PooledTierSelectorStrategy
extends AbstractTierSelectorStrategy

A TierSelectorStrategy that pools servers with the configured set of priorities from PooledTierSelectorStrategyConfig.getPriorities() and delegates server selection to the configured ServerSelectorStrategy.

Unlike other TierSelectorStrategy like CustomTierSelectorStrategy which has a preference for priority order, this strategy treats all configured priorities equally by combining their servers into a single selection pool and delegates to ServerSelectorStrategy to do the server selection. If no servers match the configured priorities in the pool, an empty server list is returned, which may cause queries to return partial or no data.

Example configuration:

druid.broker.select.tier=pooled

druid.broker.select.tier.pooled.priorities=[2,1]

With this configuration, servers with priority 2 and 1 are pooled together and selection is delegated to the ServerSelectorStrategy. Servers with other priorities are ignored.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	TYPE

Fields inherited from class org.apache.druid.client.selector.AbstractTierSelectorStrategy

serverSelectorStrategy

Constructor Summary

Constructors

Constructor	Description
PooledTierSelectorStrategy(ServerSelectorStrategy serverSelectorStrategy, PooledTierSelectorStrategyConfig config, ServiceEmitter emitter)

Method Summary

Modifier and Type	Method	Description
Comparator<Integer>	getComparator()
PooledTierSelectorStrategyConfig	getConfig()
<T> List<QueryableDruidServer>	pick(Query<T> query, it.unimi.dsi.fastutil.ints.Int2ObjectRBTreeMap<Set<QueryableDruidServer>> prioritizedServers, DataSegment segment, int numServersToPick)
String	toString()

Methods inherited from class org.apache.druid.client.selector.AbstractTierSelectorStrategy

pick

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.client.selector.TierSelectorStrategy

pick, pick

Field Details

TYPE

public static final String TYPE

See Also:

• Constant Field Values

Constructor Details

PooledTierSelectorStrategy

public PooledTierSelectorStrategy(ServerSelectorStrategy serverSelectorStrategy,
 PooledTierSelectorStrategyConfig config,
 ServiceEmitter emitter)

Method Details

pick

public <T> List<QueryableDruidServer> pick(@Nullable
 Query<T> query,
 it.unimi.dsi.fastutil.ints.Int2ObjectRBTreeMap<Set<QueryableDruidServer>> prioritizedServers,
 DataSegment segment,
 int numServersToPick)

Specified by:

pick in interface TierSelectorStrategy

Overrides:

pick in class AbstractTierSelectorStrategy

getComparator

public Comparator<Integer> getComparator()

Returns:

the natural order of priorities since priority order doesn't matter for this strategy as the configured set of priorities in the pool are treated equally and delegated to AbstractTierSelectorStrategy.serverSelectorStrategy.

getConfig

public PooledTierSelectorStrategyConfig getConfig()

toString

public String toString()

Overrides:

toString in class Object