Hi, > It would be good if the detail and what was discussed was shared with this list. > Having meetings like disadvantages those who can not attend sure to time zone or other commitments.
> Thanks Justin, I would like to add some details. Before the discussion, I created a google doc for collecting attendee list and topics. I think after the discussion, we can record the discussion and conclusion, and archive it to our confluence. Best, ----------------------------------- Xiangdong Huang School of Software, Tsinghua University 黄向东 清华大学 软件学院 Dawei Liu <[email protected]> 于2020年7月13日周一 上午9:57写道： > Hi， > > > thanks yuxin and jialin > > > Best > ——— > Dawei Liu > On 07/12/2020 20:48，Jialin Qiao<[email protected]> wrote： > Hi, > > Thanks Justin, I would like to add some details. > > We first introduced the main idea of hot compaction: When a memtable > reaches the threshold but the average number of points in each series does > not reach our goal, we flush it to a vm(virtual memory) file. After there > is enough (a configuration) vm files, we merged all vm files to the target > TsFile and close the TsFile. By this means, we could get a larger chunk > that accommodates to the query. > > The reason we call it hot compaction but not normal compaction is that the > vm is not closed, which means it only has data chunks without relating > metadata. All metadatas of vm are cached in memory. Therefore, we avoid IO, > serializing and deserializing these metadatas when doing hot compaction. It > is essentially an exchanging memory for IO and CPU. > > However, we do not have clear idea about how much percent the reading > metadata occupies in compaction. So we decided to do an experiment first. > > Thanks, > -- > Jialin Qiao > School of Software, Tsinghua University > > 乔嘉林 > 清华大学 软件学院 > > -----原始邮件----- > 发件人: "Justin Mclean" <[email protected]> > 发送时间: 2020-07-12 17:31:30 (星期日) > 收件人: dev <[email protected]> > 抄送: > 主题: Re: [Weekly Report] IoTDB Weekly News (2020-07-04~2020-07-12) > > Hi, > > [Big Event] > # We held the first online discussion yesterday, looking forward to more > attendances next time. > > It would be good if the detail and what was discussed was shared with this > list. > > Having meetings like disadvantages those who can not attend sure to time > zone or other commitments. > > Thanks, > Justin >
