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From kocol...@apache.org
Subject [2/2] couchdb commit: updated refs/heads/2735-duplicate-docs to 47d7b05
Date Sat, 18 Jul 2015 11:29:15 GMT
Ensure doc groups are sorted before merging them

We had been implicily assuming that clients send us sorted groups, but
unsurprisingly that's not always the case. The additional sorting here
should be redundant, but the consequences of merging unsorted groups are
severe -- we can end up with uniqueness violations on the primary key in
the database -- and so we add an additional sort here.

COUCHDB-2735


Project: http://git-wip-us.apache.org/repos/asf/couchdb/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb/commit/47d7b05f
Tree: http://git-wip-us.apache.org/repos/asf/couchdb/tree/47d7b05f
Diff: http://git-wip-us.apache.org/repos/asf/couchdb/diff/47d7b05f

Branch: refs/heads/2735-duplicate-docs
Commit: 47d7b05fa63cb77ed7852a5d20f86720e6ac8de1
Parents: 5b1b3e1
Author: Adam Kocoloski <adam@cloudant.com>
Authored: Fri Jul 17 19:20:36 2015 -0400
Committer: Adam Kocoloski <adam@cloudant.com>
Committed: Fri Jul 17 19:20:36 2015 -0400

----------------------------------------------------------------------
 src/couchdb/couch_db_updater.erl | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/couchdb/blob/47d7b05f/src/couchdb/couch_db_updater.erl
----------------------------------------------------------------------
diff --git a/src/couchdb/couch_db_updater.erl b/src/couchdb/couch_db_updater.erl
index 947669c..c92097f 100644
--- a/src/couchdb/couch_db_updater.erl
+++ b/src/couchdb/couch_db_updater.erl
@@ -222,7 +222,7 @@ handle_cast(Msg, #db{name = Name} = Db) ->
 
 handle_info({update_docs, Client, GroupedDocs, NonRepDocs, MergeConflicts,
         FullCommit}, Db) ->
-    GroupedDocs2 = [[{Client, D} || D <- DocGroup] || DocGroup <- GroupedDocs],
+    GroupedDocs2 = sort_and_tag_groups(Client, GroupedDocs),
     if NonRepDocs == [] ->
         {GroupedDocs3, Clients, FullCommit2} = collect_updates(GroupedDocs2,
                 [Client], MergeConflicts, FullCommit);
@@ -291,8 +291,7 @@ collect_updates(GroupedDocsAcc, ClientsAcc, MergeConflicts, FullCommit)
->
         % updaters than deal with their possible conflicts, and local docs
         % writes are relatively rare. Can be optmized later if really needed.
         {update_docs, Client, GroupedDocs, [], MergeConflicts, FullCommit2} ->
-            GroupedDocs2 = [[{Client, Doc} || Doc <- DocGroup]
-                    || DocGroup <- GroupedDocs],
+            GroupedDocs2 = sort_and_tag_groups(Client, GroupedDocs),
             GroupedDocsAcc2 =
                 merge_updates(GroupedDocsAcc, GroupedDocs2, []),
             collect_updates(GroupedDocsAcc2, [Client | ClientsAcc],
@@ -302,6 +301,15 @@ collect_updates(GroupedDocsAcc, ClientsAcc, MergeConflicts, FullCommit)
->
     end.
 
 
+sort_and_tag_groups(Client, GroupedDocs) ->
+    % These groups should already be sorted but sometimes clients misbehave.
+    % The merge_updates function will fail and the database can end up with
+    % duplicate documents if the incoming groups are not sorted, so as a sanity
+    % check we sort them again here. See COUCHDB-2735.
+    Cmp = fun([{#doc{id=A}, _}|_], [{#doc{id=B}, _}|_]) -> A < B end,
+    SortedGroups = lists:sort(Cmp, GroupedDocs),
+    [[{Client, D} || D <- DocGroup] || DocGroup <- SortedGroups].
+
 btree_by_seq_split(#doc_info{id=Id, high_seq=KeySeq, revs=Revs}) ->
     {RevInfos, DeletedRevInfos} = lists:foldl(
         fun(#rev_info{deleted = false, seq = Seq} = Ri, {Acc, AccDel}) ->


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