ES写入一致性原理
原文
To prevent writes from taking place on the "wrong" side of a network partition, by default, index operations only succeed if a quorum (>replicas/2+1) of active shards are available. This default can be overridden on a node-by-node basis using the action.write_consistency setting. To alter this behavior per-operation, the consistency request parameter can be used.
Valid write consistency values are one, quorum, and all.
Note, for the case where the number of replicas is 1 (total of 2 copies of the data), then the default behavior is to succeed if 1 copy (the primary) can perform the write.
The index operation only returns after all active shards within the replication group have indexed the document (sync replication).