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https://issues.apache.org/jira/browse/COUCHDB-2886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15022194#comment-15022194
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Robert Newson commented on COUCHDB-2886:
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The rev values are not supposed to be unique, so don't worry about those.
They're calculated from document content and history, it's deliberately the
case that two documents with identical history end up with the same _rev value
(a replication optimisation).
You can rebuild the view by truncating the .view file, couchdb will rebuild it
when you next query. You should not need to restart couchdb.
> 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: corrupt-db.zip, 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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