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https://issues.apache.org/jira/browse/IOTDB-804?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17175727#comment-17175727
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Rong Kang commented on IOTDB-804:
---------------------------------
h1. Index StorageGroup Metadata File: lifecylte
The index-framework maintains a sliding window to move over a time series.
However, the time series will be cut off due to memory-table-flushing and
TsFile closing. The indexFile will be closed with the closing of TsFile.
In view of the continuity of the sliding window, after the indexFile is closed,
the corresponding IndexStorageGroup will temporarily store the latest time
series in memory for initialization when the next indexFile is created. When
IndexStorageGroup is closed, these temporary time series data are written to
disk as *IndexSGMetadata*, which is located at
_index_root_dir/meta/[sg_name].sg_index_.
*IndexSGMetadata File Create:* when the IndexStorageGroupProcessor is closed.
It happens in the IoTDB Server is stopped. In the current version,
IndexStorageGroupProcessor won't be closed along with the StorageGroupProcessor
closing.
*IndexSGMetadata File* *Update:* when a new metafile is flush out, it will
replace the old one.
*IndexSGMetadata File* *Delete:* when system is restarted,
`IndexManager#cleanIndexData` will check exist files and folders in
index_root_dir. For all storage groups, whose indexes have been dropped, their
IndexSGMetadata files and index data will be deleted.
> Index Framework
> ---------------
>
> Key: IOTDB-804
> URL: https://issues.apache.org/jira/browse/IOTDB-804
> Project: Apache IoTDB
> Issue Type: New Feature
> Components: Core/Engine
> Reporter: Rong Kang
> Priority: Major
>
> Implement the index framework in IoTDB, supporting the time-series index:
> creation, building and query.
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