Hi, I submitted a pr to add an order-by-heat feature in show time series syntax.
PR: https://github.com/apache/incubator-iotdb/pull/1341 ISSUE-1281: https://github.com/apache/incubator-iotdb/issues/1281 Best, --------------- Yuan Tian > -----原始邮件----- > 发件人: "田原" <[email protected]> > 发送时间: 2020-06-10 15:29:16 (星期三) > 收件人: [email protected] > 抄送: > 主题: [ISSUE-1281] Show timeseries in descending ordered of last point time > > Hi, > > > I'm working on the > issue-1281(https://github.com/apache/incubator-iotdb/issues/1281). I plan to > add a sub clause in show timeseries syntax, like: > > > SHOW TIMESERIES prefixPath? showWhereClause? orderByHeatClause? limitClause? > > > The 'orderByHeatClause' is added to support this feature. The detailed syntax > is: > > > orderByHeatClause > : ORDER BY HEAT > ; > > > It's an optional clause, if user doesn't specify it. The action of 'show > timeseries' will just be like before, the result set is sorted by the > registered time of the time series. > > > If it is specified, firstly we will obtain all the satisfying timeseries as > before, then we will sort them by the last point's timestamp. That means if > the timeseries is inserted recently, it will be shown in the front. > > > In the implementation, as we have got the LeafMNode before, so we can use the > cachedLastValuePair field in it to get last timestamp, if the > cachedLastValuePair is null, we will construct a LastQueryPlan to get it. > > > Best, > --------------- > Yuan Tian
