org.apache.hadoop.contrib.index.mapred
Interface IDistributionPolicy

All Known Implementing Classes:

HashingDistributionPolicy, RoundRobinDistributionPolicy

public interface IDistributionPolicy

A distribution policy decides, given a document with a document id, which one shard the request should be sent to if the request is an insert, and which shard(s) the request should be sent to if the request is a delete.

Method Summary

int	chooseShardForDelete(DocumentID key) Choose a shard or all shards to send a delete request.
int	chooseShardForInsert(DocumentID key) Choose a shard to send an insert request.
void	init(Shard[] shards) Initialization.

Method Detail

init

void init(Shard[] shards)

Initialization. It must be called before any chooseShard() is called.

Parameters:

shards -

chooseShardForInsert

int chooseShardForInsert(DocumentID key)

Choose a shard to send an insert request.

Parameters:

key -

Returns:

the index of the chosen shard

chooseShardForDelete

int chooseShardForDelete(DocumentID key)

Choose a shard or all shards to send a delete request. E.g. a round-robin distribution policy would send a delete request to all the shards. -1 represents all the shards.

Parameters:

key -

Returns:

the index of the chosen shard, -1 if all the shards are chosen