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https://issues.apache.org/jira/browse/COUCHDB-2886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15014217#comment-15014217
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Robert Newson commented on COUCHDB-2886:
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Hi,
Are the documents corrupted or just the view?
> Concurrent Bulk Updates and Attachments yield Corruption
> ---------------------------------------------------------
>
> Key: COUCHDB-2886
> URL: https://issues.apache.org/jira/browse/COUCHDB-2886
> Project: CouchDB
> Issue Type: Bug
> Reporter: Steven Schaefer
> Attachments: couch_corrupter.zip
>
>
> I work for Nexidia, and we're evaluating CouchDB for a new system we're
> developing. I was running some tests and in general trying to push it as hard
> as I could to help gain experience and set expectations, and I've encountered
> what appears to be a database corruption issue, when conflicting concurrent
> batch updates include attachments. I noticed results from one of my views
> made no sense, and after verifying it was up-to-date, tried running view
> compaction in an attempt to address that problem. It errored with this:
> {quote}
> [info] [<0.24269.24>] Compaction started for db: bug idx: _design/dev
> [info] [<0.24224.24>] 127.0.0.1 - - POST /bug/_compact/dev 202
> [error] [<0.24269.24>] Duplicate docid `9255f05ad2939b5c487209321c000c79`
> detected in view group `_design/dev`, database `bug` - This view needs to be
> rebuilt.
> [error] [<0.24251.24>] ** Generic server <0.24251.24> terminating
> ** Last message in was {'EXIT',<0.24269.24>,
> {view_duplicate_id,
> <<"9255f05ad2939b5c487209321c000c79">>}}
> ** When Server state == {st,<0.24244.24>,couch_mrview_index,<0.24269.24>}
> ** Reason for termination ==
> ** unknown_info
> {quote}
> Deleting and then rebuilding the view didn't help, after which view results
> were still incorrect, and re-running view compaction produced the same error,
> which suggests to me a more fundamental issue.
> I narrowed it down to a combination of concurrent bulk updates with
> attachments, or at least I should say I can consistently reproduce when
> including attachments, but I could never reproduce without them. I have
> attached a smallish example that usually reproduces the issue on my system.
> Notes for running:
> * Depends on Java 8 and if compiling I set this up to use maven
> * Program will create "bug" database in a Couch instance running at
> localhost:5984. An existing "bug" db will be deleted.
> * Some variables may need to be altered depending on system specs, look for
> "NOTE:" in the code. Rebuilding should be as easy as (assuming maven is
> installed) running from wherever unzipped: mvn install
> * run-test.bat provides the command to run it. Only adjusting the -cp
> parameter should be necessary for Linux (i.e. ';' --> ':' )
> * Should run fairly quickly, after which "Bug reproduced" should be visible
> in the console, and the Couch log will have an error like above.
> System Notes:
> * Windows 7
> * 2x Intel Xeon E5-2687W v3 @ 3.10 GHz - 10 cores + hyperthreading (40
> logical processors)
> * 32 GB ram (NUMA)
> * CouchDB configuration is default except for db and view storage locations.
> * CouchDB 1.6.1
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