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https://issues.apache.org/jira/browse/COUCHDB-968?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Adam Kocoloski reopened COUCHDB-968:
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It turns out this series of patches does not merge key trees correctly in all
cases. It wrongly assumes that the "InsertTree" is always a linear path. Now,
it is true that every invocation of couch_key_tree:merge/2 has a linear
revision path in the 2nd argument. However, when couch_key_tree:merge_one/4
successfully merges the inserted revision path into one of the branches of an
existing tree, creating a new "Merged" branch, it turns around and tries to
merge that Merged branch into the next branch of the tree. At this point, all
bets are off -- the new InsertTree (a.k.a. Merged) is a full revision tree and
can have an arbitrary number of siblings at each level.
I believe this commit addresses the issue:
https://github.com/kocolosk/couchdb/commit/a542113796653c6ff3673e05563fa20f041e6983
> Duplicated IDs in _all_docs
> ---------------------------
>
> Key: COUCHDB-968
> URL: https://issues.apache.org/jira/browse/COUCHDB-968
> Project: CouchDB
> Issue Type: Bug
> Components: Database Core
> Affects Versions: 0.10.1, 0.10.2, 0.11.1, 0.11.2, 1.0, 1.0.1, 1.0.2
> Environment: any
> Reporter: Sebastian Cohnen
> Assignee: Adam Kocoloski
> Priority: Blocker
> Fix For: 0.11.3, 1.0.2, 1.1
>
>
> We have a database, which is causing serious trouble with compaction and
> replication (huge memory and cpu usage, often causing couchdb to crash b/c
> all system memory is exhausted). Yesterday we discovered that db/_all_docs is
> reporting duplicated IDs (see [1]). Until a few minutes ago we thought that
> there are only few duplicates but today I took a closer look and I found 10
> IDs which sum up to a total of 922 duplicates. Some of them have only 1
> duplicate, others have hundreds.
> Some facts about the database in question:
> * ~13k documents, with 3-5k revs each
> * all duplicated documents are in conflict (with 1 up to 14 conflicts)
> * compaction is run on a daily bases
> * several thousands updates per hour
> * multi-master setup with pull replication from each other
> * delayed_commits=false on all nodes
> * used couchdb versions 1.0.0 and 1.0.x (*)
> Unfortunately the database's contents are confidential and I'm not allowed to
> publish it.
> [1]: Part of http://localhost:5984/DBNAME/_all_docs
> ...
> {"id":"9997","key":"9997","value":{"rev":"6096-603c68c1fa90ac3f56cf53771337ac9f"}},
> {"id":"9999","key":"9999","value":{"rev":"6097-3c873ccf6875ff3c4e2c6fa264c6a180"}},
> {"id":"9999","key":"9999","value":{"rev":"6097-3c873ccf6875ff3c4e2c6fa264c6a180"}},
> ...
> [*]
> There were two (old) servers (1.0.0) in production (already having the
> replication and compaction issues). Then two servers (1.0.x) were added and
> replication was set up to bring them in sync with the old production servers
> since the two new servers were meant to replace the old ones (to update
> node.js application code among other things).
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