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https://issues.apache.org/jira/browse/PHOENIX-5494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16987521#comment-16987521
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Lars Hofhansl edited comment on PHOENIX-5494 at 12/4/19 4:41 AM:
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It's all about how what percentage of the time is spent in setting up the
scanners seeking per row.
In my test I ran this with WAL writing turned off, and I tested with local
indexes, so that percentage improvement would be larger, although the absolute
improvement would be the same.
33% end-to-end is nothing to scoff about!
was (Author: lhofhansl):
It's all about how what percentage of the time is spent in setting up the
scanners seeking per row.
In my test I ran this with WAL writing turned off, so that percentage
improvement would be larger, although the same absolute terms. 33% end-to-end
is nothing to scoff about!
> Batched, mutable Index updates are unnecessarily run one-by-one
> ---------------------------------------------------------------
>
> Key: PHOENIX-5494
> URL: https://issues.apache.org/jira/browse/PHOENIX-5494
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 4.15.0, 5.1.0
> Reporter: Lars Hofhansl
> Assignee: chenglei
> Priority: Major
> Labels: performance
> Fix For: 4.15.0, 5.1.0
>
> Attachments: 5494-4.x-HBase-1.5.txt,
> PHOENIX-5494-4.x-HBase-1.4.patch, PHOENIX-5494.master.001.patch,
> PHOENIX-5494.master.002.patch, PHOENIX-5494.master.003.patch,
> PHOENIX-5494_v9-4.x-HBase-1.4.patch, PHOENIX-5494_v9-master.patch,
> Screenshot_20191110_160243.png, Screenshot_20191110_160351.png,
> Screenshot_20191110_161453.png
>
> Time Spent: 5h 50m
> Remaining Estimate: 0h
>
> I just noticed that index updates on mutable tables retrieve their deletes
> (to invalidate the old index entry) one-by-one.
> For batches, this can be *the* major time spent during an index update. The
> cost is mostly incured by the repeated setup (and seeking) of the new region
> scanner (for each row).
> We can instead do a skip scan and get all updates in a single scan per region.
> (Logically that is simple, but it will require some refactoring)
> I won't be getting to this, but recording it here in case someone feels
> inclined.
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