ondra-novak commented on issue #1235: Idea: Bring back all_or_nothing URL: https://github.com/apache/couchdb/issues/1235#issuecomment-376330010 Okaj, let's assume that this is about a new feature. 1. We have a document with conflicts. There is main revision and the one or more conflicted revisions (deleted conflicts are not included) 2. Let there is some automate process which is able to merge the most of conflicts 3. The automate process creates a new main document and then a set of delete requests for conflicted revisions. The conflicted revision is deleted by simple putting _deleted flag into it. 4. The _bulk_docs request is prepared and send to couchdb 5. - question of the ordering? Is it better to put main revision as the first or as the last? With clustered database, this is hard to decide. In my code, i always put the main revision as the last, because if the changes are applied in the order - it is single document mapped to single shard(?) - the changes feed will contain deleted conflicts as the first and then the updated main revision. 6. Now, we have VDU. The purpose of VDU is also to detected malformed merged documents. 7. however, the VDU rejects the malformed document, but it cannot reject deletion of the conflict. 8. As the result, the conflicted revisions are deleted (and lost after compaction). The main revision is not updated, so updates are also lost. The workaround is to reconstruct conflicted documents back using the data temporary stored in the memory of that automated process - but this is very ugly solution. It would be better to call VDU on the main revision and test it before the write Hmm, other workaround is to send main revision as the single request and delete conflicts only if the request passes. This has other issues. It needs two request. The new revision of the main document can be replicated and it still looks like conflicted, because conflicts has not been deleted yet. There can be also another process (for instance on other replica) which will try to merge conflicts with already updated revision. So this is the reason, why I am sending updated document as the last item To improve the work with conflicts i have just another suggestion, the field "_merged", but this will need an another ticket and looks more complicated than above suggestion.
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