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https://issues.apache.org/jira/browse/CASSANDRA-11623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15250483#comment-15250483
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Tom Petracca edited comment on CASSANDRA-11623 at 4/20/16 7:07 PM:
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A solution to this is to just estimate the size of the written file.
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[2.2|https://github.com/tpetracca/cassandra/commit/d9028ce6be8956279807b428ff55d38ae759b1de]
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[3.0|https://github.com/tpetracca/cassandra/commit/a1c8d32e9443536e58b1fac164981e8c01f30d9f]
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[3.5|https://github.com/tpetracca/cassandra/commit/08e1f26569339f74f146b073351e2ca7cf1ba5a7]
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[trunk|https://github.com/tpetracca/cassandra/commit/6abe3d9401b1fba00885389c7870884bda8b7d0f]
- this was the only clean cherry-pick (from 3.5)
was (Author: tpetracca):
A solution to this is to just estimate the size of the written file.
https://github.com/tpetracca/cassandra/commit/d9028ce6be8956279807b428ff55d38ae759b1de
> Compactions w/ Short Rows Spending Time in getOnDiskFilePointer
> ---------------------------------------------------------------
>
> Key: CASSANDRA-11623
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11623
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Tom Petracca
> Priority: Minor
> Attachments: compactiontask_profile.png
>
>
> Been doing some performance tuning and profiling of my cassandra cluster and
> noticed that compaction speeds for my tables that I know to have very short
> rows were going particularly slowly. Profiling shows a ton of time being
> spent in BigTableWriter.getOnDiskFilePointer(), and attaching strace to a
> CompactionTask shows that a majority of time is being spent lseek (called by
> getOnDiskFilePointer), and not read or write.
> Going deeper it looks like we call getOnDiskFilePointer each row (sometimes
> multiple times per row) in order to see if we've reached our expected sstable
> size and should start a new writer. This is pretty unnecessary.
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