Hi, > since renaming is not very frequent, maybe we do not need to worry about performance.
Ah... I remember that there is a file whose name is "version-xxx", in which the "xxx" is a counter, and will be updated if the version difference between the disk and memory >= 50. I am not sure whether it is correct that "renaming is not very frequent" because each ChunkGroup has a version (am I right?).. But, I am not saying that writing on HDFS is bad, I just want to remind you that reducing renaming operations, or proving that renaming on HDFS is not a time consuming operation. Best, ----------------------------------- Xiangdong Huang School of Software, Tsinghua University 黄向东 清华大学 软件学院 Zesong Sun <[email protected]> 于2019年8月31日周六 下午8:28写道： > Hi, > > > This issue is a sub-task of IoTDB-187 [1], which enables users to choose > whether files are storied in local file system or HDFS. > > > In this sub-task, I intend to use an encapsulated "File" to replace > existed Java File in our project. > > > Currently in our design, all files could be written on HDFS. > > > HDFS supports truncating files, and since renaming is not very frequent, > maybe we do not need to worry about performance. > > > If anyone has any other ideas, please discuss with me. > > > [1] https://issues.apache.org/jira/browse/IOTDB-187 > > > ------------------ > Zesong Sun > School of Software, Tsinghua University > > 孙泽嵩 > 清华大学 软件学院 > > > > > > > > ------------------ 原始邮件 ------------------ > 发件人: "Xiangdong Huang"<[email protected]>; > 发送时间: 2019年8月31日(星期六) 晚上10:50 > 收件人: "dev"<[email protected]>; > > 主题: [IoTDB-189] question about the feature of compatibility of HDFS > > > > Hi, > > This issue only has a title.. without any description... > > I think it is for letting IoTDB write TsFiles on HDFS directly. > > My question is, is only TsFile written on HDFS? or all files (e.g., wal, > system data file)? > > Besides, if all files are on HDFS, do we need to avoid using File name as a > mark or a lock (i.e., create a file and then rename it) for performance > consideration? > > (I am on my trip and then I realize clearly that current info on issue is > not enough for guys who are on the internet) > > Best, > ----------------------------------- > Xiangdong Huang > School of Software, Tsinghua University > > 黄向东 > 清华大学 软件学院
