[jira] [Commented] (NIFI-5064) Fixes and improvements to PutKudu processor

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-5064?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16431788#comment-16431788 ] 

ASF GitHub Bot commented on NIFI-5064:
--------------------------------------

GitHub user junegunn opened a pull request:

    https://github.com/apache/nifi/pull/2621

    NIFI-5064 Fixes and improvements to PutKudu processor

    Thank you for submitting a contribution to Apache NiFi.
    
    In order to streamline the review of the contribution we ask you
    to ensure the following steps have been taken:
    
    ### For all changes:
    - [x] Is there a JIRA ticket associated with this PR? Is it referenced 
         in the commit message?
    
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        - *No, I intentionally made separate commits so that it's easier to review each change.*
    
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You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/junegunn/nifi put-kudu-improvements

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/nifi/pull/2621.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #2621
    
----
commit f5b9ed17e47fb463d84f15c873dcaab84fdf685f
Author: Junegunn Choi <ju...@...>
Date:   2018-04-03T07:36:54Z

    Bump kudu-client version to 1.7.0

commit e4b9abcc98b3fa8f55b522f7302b80841f3df123
Author: Junegunn Choi <ju...@...>
Date:   2018-04-03T07:40:24Z

    Deprecate "Skip head line" property of PutKudu

commit 8672a4ddba0c146dfd05fee263bb9f2df8cfc1b7
Author: Junegunn Choi <ju...@...>
Date:   2018-04-03T07:38:07Z

    Fix IllegalArgumentException on 16-bit integer columns

commit 9e8305710ec7111ecd8c7cc214abeeefa51f6219
Author: Junegunn Choi <ju...@...>
Date:   2018-04-06T04:45:46Z

    Fix IllegalArgumentException on 8-bit integer columns

commit 71c2e9fc6b142ee0b7177948cf7497077e6596c4
Author: Junegunn Choi <ju...@...>
Date:   2018-04-03T07:39:13Z

    Fix NullPointerException on null/missing values

commit ab8f7047a79ddd60a9c061bb58c192bda813ea46
Author: Junegunn Choi <ju...@...>
Date:   2018-04-06T04:48:39Z

    Add support for DECIMAL types

commit 77ed66946e7bf627e15f17aa488a49b39918f0ee
Author: Junegunn Choi <ju...@...>
Date:   2018-04-10T04:48:59Z

    Fix PutKudu to properly handle server-side errors

----


> Fixes and improvements to PutKudu processor
> -------------------------------------------
>
>                 Key: NIFI-5064
>                 URL: https://issues.apache.org/jira/browse/NIFI-5064
>             Project: Apache NiFi
>          Issue Type: Improvement
>    Affects Versions: 1.6.0
>            Reporter: Junegunn Choi
>            Priority: Major
>
> 1. Currently, PutKudu fails with NPE on null or missing values.
> 2. {{IllegalArgumentException}} on 16-bit integer columns because of [a missing {{break}} in case clause for INT16 columns|https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-nar-bundles/nifi-kudu-bundle/nifi-kudu-processors/src/main/java/org/apache/nifi/processors/kudu/PutKudu.java#L112-L115].
> 3. Also, {{IllegalArgumentException}} on 8-bit integer columns. We need a separate case clause for INT8 columns where {{PartialRow#addByte}} instead of {{PartialRow#addShort}} is be used.
> 4. NIFI-4384 added batch size parameter, however, it only applies to FlowFiles with multiple records. {{KuduSession}} is created and closed for each FlowFile, so if a FlowFile contains only a single record, no batching takes place. A workaround would be to use a preprocessor to concatenate multiple FlowFiles, but since {{PutHBase}} and {{PutSQL}} use {{session.get(batchSize)}} to handle multiple FlowFiles at once, I think we can take the same approach here with PutKudu as it simplifies the data flow.
> 5. {{PutKudu}} depends on kudu-client 1.3.0. But we can safely update to 1.7.0.
>  - [https://github.com/apache/kudu/blob/1.7.0/docs/release_notes.adoc]
>  - [https://github.com/apache/kudu/blob/1.7.0/docs/prior_release_notes.adoc]
> A notable change in Kudu 1.7.0 is the addition of Decimal type.
> 6. {{PutKudu}} has {{Skip head line}} property for ignoring the first record in a FlowFile. I suppose this was added to handle header lines in CSV files, but I really don't think it's something {{PutKudu}} should handle. {{CSVReader}} already has {{Treat First Line as Header}} option, so we should tell the users to use it instead as we don't want to have the same option here and there. Also, the default value of {{Skip head line}} is {{true}}, and I found it very confusing as my use case was to stream-process single-record FlowFiles. We can keep this property for backward compatibility, but we should at least deprecate it and change the default value to {{false}}.
> 7. Server-side errors such as uniqueness constraint violation are not checked and simply ignored. When flush mode is set to {{AUTO_FLUSH_SYNC}}, we should check the return value of {{KuduSession#apply}} to see it has {{RowError}}, but PutKudu currently ignores it. For example, on uniqueness constraint violation, we get a {{RowError}} saying "_Already present: key already present (error 0)_".
> On the other hand, when flush mode is set to {{AUTO_FLUSH_BACKGROUND}}, {{KuduSession#apply}}, understandably, returns null, and we should check the return value of {{KuduSession#getPendingErrors()}}. And when the mode is {{MANUAL_FLUSH}}, we should examine the return value of {{KuduSession#flush()}} or {{KuduSession#close()}}. In this case, we also have to make sure that we don't overflow the mutation buffer of {{KuduSession}} by calling {{flush()}} before too late.
> ----
> I'll create a pull request on GitHub. Since there are multiple issues to be addressed. I made separate commits for each issue mentioned above so that it's easier to review. You might want to squash them into one, or cherry-pick a subset of commits if you don't agree with some decisions I made.
> Please let me know what you think. We deployed the code to a production server last week and it's been running since without any issues steadily processing 20K records/second.



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