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https://issues.apache.org/jira/browse/CASSANDRA-11053?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15206402#comment-15206402
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Adam Holmberg commented on CASSANDRA-11053:
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Changes look good. +1 at 07854f8
> COPY FROM on large datasets: fix progress report and debug performance
> ----------------------------------------------------------------------
>
> Key: CASSANDRA-11053
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11053
> Project: Cassandra
> Issue Type: Bug
> Components: Tools
> Reporter: Stefania
> Assignee: Stefania
> Labels: doc-impacting
> Fix For: 2.1.14, 2.2.6, 3.0.5, 3.5
>
> Attachments: bisect_test.py, copy_from_large_benchmark.txt,
> copy_from_large_benchmark_2.txt, parent_profile.txt, parent_profile_2.txt,
> worker_profiles.txt, worker_profiles_2.txt
>
>
> h5. Description
> Running COPY from on a large dataset (20G divided in 20M records) revealed
> two issues:
> * The progress report is incorrect, it is very slow until almost the end of
> the test at which point it catches up extremely quickly.
> * The performance in rows per second is similar to running smaller tests with
> a smaller cluster locally (approx 35,000 rows per second). As a comparison,
> cassandra-stress manages 50,000 rows per second under the same set-up,
> therefore resulting 1.5 times faster.
> See attached file _copy_from_large_benchmark.txt_ for the benchmark details.
> h5. Doc-impacting changes to COPY FROM options
> * A new option was added: PREPAREDSTATEMENTS - it indicates if prepared
> statements should be used; it defaults to true.
> * The default value of CHUNKSIZE changed from 1000 to 5000.
> * The default value of MINBATCHSIZE changed from 2 to 10.
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