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From "Stefania (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-11053) COPY FROM on large datasets: fix progress report and debug performance
Date Tue, 22 Mar 2016 02:07:25 GMT


Stefania commented on CASSANDRA-11053:

Thank you for the review, I've applied all 3 suggestions in [this commit|].
It merges cleanly upwards to all branches.

I wasn't aware of the Queue module, that's why I chose a lower level approach based on deque+Event.
There aren't any recoverable exceptions as far as I can see, but I've added exception handling
anyway to be on the safe side.

> COPY FROM on large datasets: fix progress report and debug performance
> ----------------------------------------------------------------------
>                 Key: CASSANDRA-11053
>                 URL:
>             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: 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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