Package org.apache.druid.client.selector

Class StrictTierSelectorStrategy

java.lang.Object

org.apache.druid.client.selector.AbstractTierSelectorStrategy

org.apache.druid.client.selector.StrictTierSelectorStrategy

All Implemented Interfaces:

TierSelectorStrategy

public class StrictTierSelectorStrategy
extends AbstractTierSelectorStrategy

A TierSelectorStrategy that only considers servers whose priorities are explicitly listed in StrictTierSelectorStrategyConfig.getPriorities().

Unlike other strategies like CustomTierSelectorStrategy that fall back to servers with different priorities, this strategy strictly filters the available servers to the configured priorities. If no servers match the configured priorities, an empty server list is returned from pick(Query, Int2ObjectRBTreeMap, DataSegment, int), which may cause queries to return partial or no data.

When multiple priorities are configured, they are evaluated in the order specified, with earlier priorities preferred over later ones.

Example configuration:

druid.broker.select.tier=strict

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

With this configuration, servers with priority 2 are preferred over servers with priority 1. Servers with any other tier priority are not considered.

This strategy is useful when query isolation is required between different server priority tiers. Brokers may still be configured to watch all server tiers, allowing them to retain visibility into the overall cluster state while enforcing isolation at query time.

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
StrictTierSelectorStrategy(ServerSelectorStrategy serverSelectorStrategy, StrictTierSelectorStrategyConfig config, ServiceEmitter emitter)

Method Summary

Modifier and Type	Method	Description
Comparator<Integer>	getComparator()
StrictTierSelectorStrategyConfig	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

StrictTierSelectorStrategy

public StrictTierSelectorStrategy(ServerSelectorStrategy serverSelectorStrategy,
 StrictTierSelectorStrategyConfig 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()

getConfig

public StrictTierSelectorStrategyConfig getConfig()

toString

public String toString()

Overrides:

toString in class Object