[
https://issues.apache.org/jira/browse/HBASE-17177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15714238#comment-15714238
]
Duo Zhang commented on HBASE-17177:
-----------------------------------
Oh I made a mistake... Even minor compaction could also reclaim the delete
cells, the difference of major compaction is that it can reclaim the delete
marker itself...
So in general, we need to record a mvcc below which we may delete some cells
and you may not read all the cells. And when a region is newly opened, we need
to freeze this value for a small amount(maybe the scanner TTL as [~yangzhe1991]
proposed above), either by disable compaction or set KeepDeleteCells to true
when compaction.
Thanks.
> Compaction can break the region/row level atomic when scan even if we pass
> mvcc to client
> -----------------------------------------------------------------------------------------
>
> Key: HBASE-17177
> URL: https://issues.apache.org/jira/browse/HBASE-17177
> Project: HBase
> Issue Type: Sub-task
> Components: scan
> Reporter: Duo Zhang
> Fix For: 2.0.0, 1.4.0
>
>
> We know that major compaction will actually delete the cells which are
> deleted by a delete marker. In order to give a consistent view for a scan, we
> need to use a map to track the read points for all scanners for a region, and
> the smallest one will be used for a compaction. For all delete markers whose
> mvcc is greater than this value, we will not use it to delete other cells.
> And the problem for a scan restart after region move is that, the new RS does
> not have the information of the scanners opened at the old RS before the
> client sends scan requests to the new RS which means the read points map is
> incomplete and the smallest read point maybe greater than the correct value.
> So if a major compaction happens at that time, it may delete some cells which
> should be kept.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
