Module org.elasticsearch.server
Interface ShardsAllocator
- All Known Implementing Classes:
BalancedShardsAllocator,DesiredBalanceShardsAllocator
public interface ShardsAllocator
A ShardsAllocator is the main entry point for shard allocation on nodes in the cluster.
The allocator makes basic decision where a shard instance will be allocated, if already allocated instances
need to relocate to other nodes due to node failures or due to rebalancing decisions.
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Method Summary
Modifier and TypeMethodDescriptionvoidallocate(RoutingAllocation allocation) Allocates shards to nodes in the cluster.default voidallocate(RoutingAllocation allocation, ActionListener<Void> listener) Allocates shards to nodes in the cluster.decideShardAllocation(ShardRouting shard, RoutingAllocation allocation) Returns the decision for where a shard should reside in the cluster.default RoutingExplanationsexecute(RoutingAllocation allocation, AllocationCommands commands, boolean explain, boolean retryFailed) Execute allocation commands
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Method Details
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allocate
Allocates shards to nodes in the cluster. An implementation of this method should: - assign unassigned shards - relocate shards that cannot stay on a node anymore - relocate shards to find a good shard balance in the cluster- Parameters:
allocation- current node allocation
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allocate
Allocates shards to nodes in the cluster. An implementation of this method should: - assign unassigned shards - relocate shards that cannot stay on a node anymore - relocate shards to find a good shard balance in the cluster- Parameters:
allocation- current node allocationlistener- listener to be executed once async allocation is completed
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execute
default RoutingExplanations execute(RoutingAllocation allocation, AllocationCommands commands, boolean explain, boolean retryFailed) Execute allocation commands -
decideShardAllocation
Returns the decision for where a shard should reside in the cluster. If the shard is unassigned, then theAllocateUnassignedDecisionwill be non-null. If the shard is not in the unassigned state, then theMoveDecisionwill be non-null. This method is primarily used by the cluster allocation explain API to provide detailed explanations for the allocation of a single shard. Implementations of theallocate(RoutingAllocation)method may use the results of this method implementation to decide on allocating shards in the routing table to the cluster. If an implementation of this interface does not support explaining decisions for a single shard through the cluster explain API, then this method should throw aUnsupportedOperationException.
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