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https://issues.apache.org/jira/browse/IOTDB-1264?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17311270#comment-17311270
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Tian Jiang commented on IOTDB-1264:
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No, but it is easy to know how many times the file has been flushed before it
is closed, and if it is flushed only once, this solution is appliable.
> Insert unseq file to seq files when possible
> --------------------------------------------
>
> Key: IOTDB-1264
> URL: https://issues.apache.org/jira/browse/IOTDB-1264
> Project: Apache IoTDB
> Issue Type: Improvement
> Components: Core/Engine
> Reporter: Tian Jiang
> Priority: Minor
> Labels: file, unseq
>
> We judge if data belongs to the seq region or unseq region only by the
> lastFlushedTime of each device, which makes the following situation possible:
> 2 seq files and their time ranges: seq1[0, 99], seq2[300, 500]
> 1 unseq file and its time range: unseq1[150, 200]
> Intuitively, we can just make them 3 seq files, which may potentially reduce
> query overhead.
> One solution may be: right after we close one unseq file, we check if it
> actually overlaps with any seq file(s), and if not, we insert it into a
> proper position of the seq files instead of keeping it in unseq files.
> Another merit is that this avoids the case mentioned in
> https://github.com/apache/iotdb/pull/2920#pullrequestreview-623932806,
> because each unseq file will definitely overlap at least one seq file.
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