Hi, > I think we can change the name of the old Gorilla encoding to TSEncoding.OLD_GORILLA in the code under the premise of ensuring the compatibility of the old TsFiles, and then reserve TSEncoding.GORILLA for the re-implemented version. This may minimize the impact on users.
I opt for this way. Old_Gorillia still can be serialized as "6". And then we assign a new short value to the new gorilla. Best, ----------------------------------- Xiangdong Huang School of Software, Tsinghua University 黄向东 清华大学 软件学院 Steve Su <[email protected]> 于2020年10月11日周日 下午11:53写道： > Hi, > > From my point of view, since the reimplementation of this algorithm does > not change the structure of TsFile, there is no need to upgrade the version > number of TsFile to 000003. > > I think we can change the name of the old Gorilla encoding to > TSEncoding.OLD_GORILLA in the code under the premise of ensuring the > compatibility of the old TsFiles, and then reserve TSEncoding.GORILLA for > the re-implemented version. This may minimize the impact on users. > > What do you think? :) > > Steve Su > > ------------------ 原始邮件 ------------------ > 发件人: "dev" <[email protected]>; > 发送时间: 2020年10月10日(星期六) 晚上11:35 > 收件人: "dev"<[email protected]>; > 主题: Re: Share some experiment results about Gorilla encoding algorithm > > Hi, > > Nice! > > One question. So, if we reimplement the Gorilla algorithm, how to consider > the version compatibility? > > 1. Upgrade the TsFile version to 000003, or > 2. Add a new encoding name to the corrected gorilla. > > Best, > ----------------------------------- > Xiangdong Huang > School of Software, Tsinghua University > > 黄向东 > 清华大学 软件学院 > > > Steve Su <[email protected]> 于2020年10月10日周六 下午10:20写道： > > > Hi, > > > > Recently, we realized that the Gorilla encoding algorithm that has been > > used inside IoTDB may have some issues, because it will cause time series > > data (the value part) to become more space-consuming after encoding. This > > is not in line with expectations. Usually after using Gorilla encoding, > the > > data will take up less space. > > > > I found a very good open source Gorilla algorithm implementation by > > Michael on Github (see https://github.com/burmanm/gorilla-tsc). I > > compared the difference in encoding / decoding time cost and compression > > rate between the version implemented by Michael and the version used > > internally by IoTDB, and found that the version used inside IoTDB does > have > > a lot of room for improvement. > > > > See > > > https://cwiki.apache.org/confluence/display/IOTDB/Gorilla+encoding+algorithm > > for more experiment details. > > > > I think we can refer to Michael's implementation to re-implement the > > algorithm inside IoTDB to reduce the compression rate (fix potential > > errors) and improve performance. I have created a JIRA (see > > https://issues.apache.org/jira/browse/IOTDB-938) for this. If possible, > I > > would be happy to re-implement the algorithm. > > > > Thanks, > > Steve Su
