Hi Caiyin, Thank you for your contribution, I have a question regrading the definition of active metadata. Could you please provide more details on what constitutes “active metadata” in this context? Understanding this definition better will help us utilize this new feature!
Thank you again for your hard work and contribution. Best regards, Itami Sho > 2024年6月3日 11:45，Caiyin Yang <ycy...@gmail.com> 写道： > > Hello everyone, I'm Caiyin Yang, a contributor to IoTDB. > > I have implemented an active metadata query feature in IoTDB in the past > few months, which is an extension based on the original *SHOW/COUNT > DEVICES/TIMESERIES *SQL. You only need to specify the time condition in the > SQL statement (*for example: show timeseries where time > xx and time < xx*) > to know which metadata exists in that interval. > > The active metadata query first uses the statistical information in memory > for optimization, and only performs disk scanning when the statistical > information cannot be used. > > To optimize the performance of disk scanning, I implemented the sequential > scan of TsFile files called RegionScan. > > In the scenario of full scanning of active data, compared with the original > series query, there is better performance (preliminary tests have shown an > improvement of nearly 20% - 30%). I will then carry out more comprehensive > performance testing scenarios and welcome everyone to provide any feedback. > > *PR Links:* > https://github.com/apache/iotdb/pull/12446 > https://github.com/apache/iotdb/pull/12539 > https://github.com/apache/iotdb/pull/12607
