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Posted to dev@iotdb.apache.org by "suyue (JIRA)" <ji...@apache.org> on 2019/07/18 01:19:00 UTC

[jira] [Created] (IOTDB-144) MetaData cache in query

suyue created IOTDB-144:
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             Summary: MetaData cache in query
                 Key: IOTDB-144
                 URL: https://issues.apache.org/jira/browse/IOTDB-144
             Project: Apache IoTDB
          Issue Type: Improvement
            Reporter: suyue


To increase query speed, metadata needs to be cached, including TsFileMetaData and TsDeviceMetaData.
The files in IOTDB are organized according to time, so the query frequency of different files varies greatly. Cache metadatas of frequently queried files can reduce the time of reading metaData from disk. Besides, all sensors' metadata of a device is in TsDeviceMetaData. In order to read the metadata of a sensor, we need to read the entire TsDeviceMetaData. In the current version, querying multiple sensors in a device simultaneously need to read TsDeviceMetaData multiple times, so consider caching TsDeviceMetaData.



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