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https://issues.apache.org/jira/browse/IOTDB-587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17081620#comment-17081620
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Jialin Qiao commented on IOTDB-587:
-----------------------------------
[https://github.com/apache/incubator-iotdb/pull/855]
> TsFile version 2
> ----------------
>
> Key: IOTDB-587
> URL: https://issues.apache.org/jira/browse/IOTDB-587
> Project: Apache IoTDB
> Issue Type: Improvement
> Components: Core/Engine, Core/TsFile
> Reporter: Jialin Qiao
> Priority: Major
> Fix For: 0.10.0-SNAPSHOT
>
>
> This issue it to record the TsFile version 2.
> In TsFile version 1 (rel/0.9), the ChunkMetadata is stored by device. If we
> want to query one series, we need to read ChunkMetadatas of all measurements
> of its device, which is time-consuming.
> Therefore, we want to avoid this unnecessary cost. The solution is decreasing
> the granularity of ChunkMetadata from device to each series.
> In the new version, the ChunkMetadata is grouped by each time series. If we
> want to query one series, we only need to read ChunkMetadata of this series.
> A file level statistics TimeseriesMetadata is added for each series to
> accelerate aggregations.
> Besides, by modifying the schema management of TsFile, the constraints that
> measurements that have the same name in one storage group should have the
> same data type is removed.
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