I think distinguishing flushing on one node or on the cluster has its meaning.
As you said, flush can reduce memory and speed up the restart process. So, how about if the DBA just wants to restart one node.. However, the default behavior can be discussed: flush on one node by default or on the whole cluster by default. ----------------------------------- Xiangdong Huang School of Software, Tsinghua University 黄向东 清华大学 软件学院 李思佳 <[email protected]> 于2022年5月23日周一 11:28写道： > Sorry, I don't understand what the purpose and use of flushing current > datanode is. > > IMO, flush all should mean that all storage group could be flushed, in > another word, flush sg is a subset of flush all. > > For users, distributed is a black box, while SG is an exposed structure. > Therefore, for cli commands, there is no need to be aware of the > relationship between the datanode and the self-created SG. > > In addition, the Flush operation may speed up our restart recovery > process. For example, when we flush an SG successfully, we can label the > associated data files to indicate that all copies are consistent at that > point in time(here are flush and write priorities). During the next > restart, we can use this flag to quickly skip the verification step. > > In summary, here are my questions and thoughts: > 1. Is it necessary to flush a dataNode? What are the benefits of this? > 2. Can the Flush operation affect the consensus group or WAL for a quick > restart? > > BR, > ----------------------------------- > Sijia Li > > > -----邮件原件----- > 发件人: Jialin Qiao <[email protected]> > 发送时间: 2022年5月23日 11:07 > 收件人: [email protected] > 主题: Flush function in cluster > > Hi, > > Flush is a frequently used command in IoTDB, which flushes memtable into > disk and closes all tsfiles. > > In the new cluster, we need to redefine this function [1]. > > * flush: flushing current datanode > > * flush all/cluster: flushing all datanodes > > * flush sg: flush all DataRegions of a storage group > > > What do you think? > > [1] https://issues.apache.org/jira/browse/IOTDB-3099 > > ————————————————— > Jialin Qiao > Apache IoTDB PMC >
