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https://issues.apache.org/jira/browse/HBASE-13291?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14481950#comment-14481950
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Lars Hofhansl commented on HBASE-13291:
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SQM.match() was changed in truck to be expressed in term of operations on Cells
(before it was hand "optimized" to deconstruct KVs in the most efficient way).
I do not know how much that costs, but might be worth investigating.
So far our introduction of Cells has made a bunch of things slower, but since
we haven't finished I am not aware of a single perf advantage (when finished we
should be able to make block encoding and prefix tries much faster). Maybe it's
time to make a concerted effort and get rid of KeyValue.getKey() and
KeyValue.getBuffer() for real, it's those two methods that prevent a lot of
cool optimizations.
> Lift the scan ceiling
> ---------------------
>
> Key: HBASE-13291
> URL: https://issues.apache.org/jira/browse/HBASE-13291
> Project: HBase
> Issue Type: Improvement
> Components: Scanners
> Affects Versions: 1.0.0
> Reporter: stack
> Assignee: stack
> Attachments: 13291.hacks.txt, 13291.inlining.txt, Screen Shot
> 2015-03-26 at 12.12.13 PM.png, Screen Shot 2015-03-26 at 3.39.33 PM.png,
> hack_to_bypass_bb.txt, nonBBposAndInineMvccVint.txt, q (1).png,
> scan_no_mvcc_optimized.svg, traces.7.svg, traces.filterall.svg,
> traces.nofilter.svg, traces.small2.svg, traces.smaller.svg
>
>
> Scanning medium sized rows with multiple concurrent scanners exhibits
> interesting 'ceiling' properties. A server runs at about 6.7k ops a second
> using 450% of possible 1600% of CPUs when 4 clients each with 10 threads
> doing scan 1000 rows. If I add '--filterAll' argument (do not return
> results), then we run at 1450% of possible 1600% possible but we do 8k ops a
> second.
> Let me attach flame graphs for two cases. Unfortunately, there is some
> frustrating dark art going on. Let me try figure it... Filing issue in
> meantime to keep score in.
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