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https://issues.apache.org/jira/browse/HBASE-7842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13595035#comment-13595035
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Elliott Clark commented on HBASE-7842:
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bq.Can you add tests for those with new policy?
Not really it relies on Bulk loading, regular inserts, and compactions to work
together to make some strange orders of files and seq numbers. Though one of
the added tests ((251, 253, 251, maxSize -1)) should cover cover things alright.
bq.Why? What if files are 500 5?
yep off by one error. Should be < 2 rather than <= 2.
bq.Nit: not necessary.
Yes it is. If the loop never finds something that passes the pre-conditions we
need to have an empty list to return or there will be npe's.
> Add compaction policy that explores more storefile groups
> ---------------------------------------------------------
>
> Key: HBASE-7842
> URL: https://issues.apache.org/jira/browse/HBASE-7842
> Project: HBase
> Issue Type: New Feature
> Components: Compaction
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Attachments: HBASE-7842-0.patch, HBASE-7842-2.patch,
> HBASE-7842-3.patch, HBASE-7842-4.patch
>
>
> Some workloads that are not as stable can have compactions that are too large
> or too small using the current storefile selection algorithm.
> Currently:
> * Find the first file that Size(fi) <= Sum(0, i-1, FileSize(fx))
> * Ensure that there are the min number of files (if there aren't then bail
> out)
> * If there are too many files keep the larger ones.
> I would propose something like:
> * Find all sets of storefiles where every file satisfies
> ** FileSize(fi) <= Sum(0, i-1, FileSize(fx))
> ** Num files in set =< max
> ** Num Files in set >= min
> * Then pick the set of files that maximizes ((# storefiles in set) /
> Sum(FileSize(fx)))
> The thinking is that the above algorithm is pretty easy reason about, all
> files satisfy the ratio, and should rewrite the least amount of data to get
> the biggest impact in seeks.
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