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https://issues.apache.org/jira/browse/PHOENIX-5494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16972031#comment-16972031
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Lars Hofhansl commented on PHOENIX-5494:
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Just used the sampler in visualvm.
Actually you can make this much better by setting the block encoding to
ROW_INDEX_V1 (instead of FAST_DIFF) and setting compression to zSTD (from
none). That's what I had when I took the first two screenshots.
But even then we should avoid creating a region scanner over and over!
> 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
> Reporter: Lars Hofhansl
> Assignee: Kadir OZDEMIR
> Priority: Major
> Labels: performance
> Attachments: Screenshot_20191110_160243.png,
> Screenshot_20191110_160351.png, Screenshot_20191110_161453.png
>
>
> 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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