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https://issues.apache.org/jira/browse/HBASE-20525?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16462212#comment-16462212
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Guanghao Zhang commented on HBASE-20525:
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Great! +1 for refactor. Convert HBASE-19034 as a sub-task of this issue.
> Refactoring the code of read path
> ---------------------------------
>
> Key: HBASE-20525
> URL: https://issues.apache.org/jira/browse/HBASE-20525
> Project: HBase
> Issue Type: Umbrella
> Components: scan
> Reporter: Duo Zhang
> Priority: Critical
> Fix For: 3.0.0
>
>
> The known problems of the current implementation:
> 1. 'Seek or skip' should be decided at StoreFileScanner level, not
> StoreScanner.
> 2. As now we support creating multiple StoreFileReader instances for a single
> HFile, we do not need to load the file info and other meta infos every time
> when creating a new StoreFileReader instance.
> 3. 'Pread or stream' should be decided at StoreFileScanner level, not
> StoreScanner.
> 4. Make sure that we can return at any point during a scan, at least when
> filterRowKey we can not stop until we reach the next row, no matter how many
> cells we need to skip...
> 5. Doing bytes comparing everywhere, where we need to know if there is a row
> change, a family change, a qualifier change, etc. This is a performance
> killer.
> And the most important thing is that, the code is way too complicated now and
> become out of control...
> This should be done before our 3.0.0 release.
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