[ https://issues.apache.org/jira/browse/COUCHDB-902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12921743#action_12921743 ] 

Klaus Trainer commented on COUCHDB-902:
---------------------------------------

I've figured out what the actual problem here is.

========================================================================
Deleting conflicts on database two:
========================================================================
GET - /two/test?conflicts=true - "some plain text"
200 - {"_id":"test","_rev":"2-871d61d84063e8fc02d64acbcdaad8ba","foo":3,"_conflicts":["2-2ee767305024673cfb3f5af037cd2729"]}

DELETE - /two/test?rev=2-2ee767305024673cfb3f5af037cd2729 - 
200 - {"ok":true,"id":"test","rev":"3-89c964c5556795ee0fc45fd5213013b4"}

========================================================================
Attaching to document without conflicts on database two:
========================================================================
GET - /two/test - "some plain text"
200 - {"_id":"test","_rev":"2-871d61d84063e8fc02d64acbcdaad8ba","foo":3}

PUT - /two/test/some_attachment?rev=2-871d61d84063e8fc02d64acbcdaad8ba - some plain text
409 - {"error":"conflict","reason":"Document update conflict."}


The problem is that when deleting the conflicting revision 2-2ee767305024673cfb3f5af037cd2729, just a new revision 3-89c964c5556795ee0fc45fd5213013b4 (with "_deleted":true) is created. The old revision 2-871d61d84063e8fc02d64acbcdaad8ba (that's not been deleted) is now in a kind of "deleted conflict" state with it. That is, updating revision 2-871d61d84063e8fc02d64acbcdaad8ba would create a new revision that's in conflict with the deleted one.

You can check this e.g. with

curl -X GET http://127.0.0.1:5984/two/test?deleted_conflicts=true
{"_id":"test","_rev":"2-871d61d84063e8fc02d64acbcdaad8ba","foo":3,"_deleted_conflicts":["3-89c964c5556795ee0fc45fd5213013b4"]}

The actual problem here is that when updating a document with an attachment, deleted conflicts are treated like normal conflicts. Supposably there's an easy solution to that issue.

> Attachments that have recovered from conflict do not accept attachments.
> ------------------------------------------------------------------------
>
>                 Key: COUCHDB-902
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-902
>             Project: CouchDB
>          Issue Type: Bug
>          Components: Database Core
>         Environment: trunk
>            Reporter: Paul Joseph Davis
>            Priority: Critical
>         Attachments: couchdb-902-test-case.py
>
>
> Apparently if a document has been in a conflict, they will reject requests to add an attachment with a conflict error.
> I've tracked this down to couch_db_updater.erl line 501, but I'm not too familiar with this part of the code so I figured I'd fill out a ticket in case anyone else can go through this more quickly than me.
> Sure would be nice if I could attach a file when I create an issue...

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