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https://issues.apache.org/jira/browse/HBASE-17172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15714331#comment-15714331
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huaxiang sun commented on HBASE-17172:
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One more question for you, Jingcheng, :). When threshold is so big that size
for all mob files is less than this threshold, in this case, if there are _del
files, the minor mob compaction actually turns into a major mob compaction.
What is the reason behind the design? Since threshold is a user configurable
variable, user may choose to configure a large value and turns the mob
compaction into a major one, if there are _del files, compaction will take
longer than expected. Thinking about compacting 1 mob file with _del files only
for major_mob_compact case so user is aware of what is going to happen.
comments? Thanks..
> Optimize major mob compaction with _del files
> ---------------------------------------------
>
> Key: HBASE-17172
> URL: https://issues.apache.org/jira/browse/HBASE-17172
> Project: HBase
> Issue Type: Improvement
> Components: mob
> Affects Versions: 2.0.0
> Reporter: huaxiang sun
> Assignee: huaxiang sun
>
> Today, when there is a _del file in mobdir, with major mob compaction, every
> mob file will be recompacted, this causes lots of IO and slow down major mob
> compaction (may take months to finish). This needs to be improved. A few
> ideas are:
> 1) Do not compact all _del files into one, instead, compact them based on
> groups with startKey as the key. Then use firstKey/startKey to make each mob
> file to see if the _del file needs to be included for this partition.
> 2). Based on the timerange of the _del file, compaction for files after that
> timerange does not need to include the _del file as these are newer files.
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