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From "Adam Kocoloski (JIRA)" <j...@apache.org>
Subject [jira] Commented: (COUCHDB-968) Duplicated IDs in _all_docs
Date Mon, 20 Dec 2010 15:50:01 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12973231#action_12973231
] 

Adam Kocoloski commented on COUCHDB-968:
----------------------------------------

I've had this fix in production for one of our affected customers for a few days now.  I think
it does what it claims to do.  There is a catch, though - the patch does nothing about the
view groups for a corrupted DB.  Rebuilding the view groups should fix them, though I haven't
explicitly confirmed this yet.

We might be able to play some games with adding the dupes to a new purge block during compaction.
 Theoretically, this would cause the view_indexer to remove them as soon as the compaction
finishes.

> 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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