Use the correct sequence for shard replacement
The call to unpack the since sequence for _changes incorrectly filtered
the value for any shard that didn't exist. This means that any shard
that was moved ended up requiring a complete rescan which is a bug. This
just sets the update sequence to the range of the shard being replaced
rather than zero.
COUCHDB-3055
diff --git a/src/fabric_view_changes.erl b/src/fabric_view_changes.erl
index 4855989..7e329ac 100644
--- a/src/fabric_view_changes.erl
+++ b/src/fabric_view_changes.erl
@@ -432,9 +432,30 @@
Ranges = lists:usort(lists:map(Extract, Unpacked)),
Filter = fun(S) -> not lists:member(S#shard.range, Ranges) end,
Replacements = lists:filter(Filter, mem3:shards(DbName)),
- Unpacked ++ [{R, 0} || R <- Replacements]
+ Unpacked ++ [{R, get_old_seq(R, Deduped)} || R <- Replacements]
end.
+
+get_old_seq(#shard{range=R}, SinceSeqs) ->
+ case lists:keyfind(R, 2, SinceSeqs) of
+ {_Node, R, Seq} when is_number(Seq) ->
+ % Unfortunately we don't have access to the db
+ % uuid so we can't set a replacememnt here.
+ 0;
+ {Node, R, {Seq, Uuid}} ->
+ % This update seq is using the old format that
+ % didn't include the node. This information is
+ % important for replacement.
+ {Seq, Uuid, Node};
+ {_Node, R, {Seq, Uuid, EpochNode}} ->
+ % This is the newest sequence format that we
+ % can use for replacement.
+ {Seq, Uuid, EpochNode};
+ _ ->
+ 0
+ end.
+
+
changes_row(Props0) ->
Props1 = case couch_util:get_value(deleted, Props0) of
true ->
