cassandra - cassandra是否删除在replication_factor 1的新节点上重复的数据

Question

我将replication_factor 设置为1，并且我有一个节点N1 集群托管所有数据(100%，1G)。当我向集群添加新节点N2以获取一半数据时，我看到的是N1(50％，1G)，N2(50％，0.5G)。

看起来节点 N1 仍然托管所有数据，即使一半数据已在 N2 上复制。当集群中只有一份副本(replication_factor=1)时，为什么会发生这种情况？

Answer 1

您是否在 N1 节点上运行了 nodetool cleanup？通读 Nodetool's cleanup command 上的文档:

Use this command to remove unwanted data after adding a new node to the cluster. Cassandra does not automatically remove data from nodes that lose part of their partition range to a newly added node. Run nodetool cleanup on the source node and on neighboring nodes that shared the same subrange after the new node is up and running. Failure to run this command after adding a node causes Cassandra to include the old data to rebalance the load on that node.