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From rnew...@apache.org
Subject [13/24] couch commit: updated refs/heads/windsor-merge-122 to 2f3a1fd
Date Tue, 05 Aug 2014 15:02:25 GMT
Add backwards compatible key_group_level option

This adds a new btree reduce fold option called `key_group_level` that
can have the value `exact`, `0`, or `N` where `N` is any positive
integer. The reason for adding this is so that calling code can pass a
group level option instead of a function for key grouping. The important
point is that the new option uses the btree's defined `less` operator to
test equality which means that ICU collation is used for key grouping on
most views.

BugzId: 19776


Project: http://git-wip-us.apache.org/repos/asf/couchdb-couch/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb-couch/commit/1d6c18e5
Tree: http://git-wip-us.apache.org/repos/asf/couchdb-couch/tree/1d6c18e5
Diff: http://git-wip-us.apache.org/repos/asf/couchdb-couch/diff/1d6c18e5

Branch: refs/heads/windsor-merge-122
Commit: 1d6c18e54478765ba4cda4379f0504a441bf5c9e
Parents: caffc58
Author: Paul J. Davis <paul.joseph.davis@gmail.com>
Authored: Wed May 29 13:19:32 2013 -0500
Committer: Robert Newson <rnewson@apache.org>
Committed: Mon Aug 4 16:40:39 2014 +0100

----------------------------------------------------------------------
 src/couch_btree.erl | 58 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 57 insertions(+), 1 deletion(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/couchdb-couch/blob/1d6c18e5/src/couch_btree.erl
----------------------------------------------------------------------
diff --git a/src/couch_btree.erl b/src/couch_btree.erl
index 9caceb8..e9d1ea8 100644
--- a/src/couch_btree.erl
+++ b/src/couch_btree.erl
@@ -73,7 +73,7 @@ fold_reduce(#btree{root=Root}=Bt, Fun, Acc, Options) ->
     Dir = couch_util:get_value(dir, Options, fwd),
     StartKey = couch_util:get_value(start_key, Options),
     InEndRangeFun = make_key_in_end_range_function(Bt, Dir, Options),
-    KeyGroupFun = couch_util:get_value(key_group_fun, Options, fun(_,_) -> true end),
+    KeyGroupFun = get_group_fun(Bt, Options),
     try
         {ok, Acc2, GroupedRedsAcc2, GroupedKVsAcc2, GroupedKey2} =
             reduce_stream_node(Bt, Dir, Root, StartKey, InEndRangeFun, undefined, [], [],
@@ -103,6 +103,62 @@ size(#btree{root = {_P, _Red}}) ->
 size(#btree{root = {_P, _Red, Size}}) ->
     Size.
 
+get_group_fun(Bt, Options) ->
+    case couch_util:get_value(key_group_level, Options) of
+        exact ->
+            make_group_fun(Bt, exact);
+        0 ->
+            fun(_, _) -> true end;
+        N when is_integer(N), N > 0 ->
+            make_group_fun(Bt, N);
+        undefined ->
+            couch_util:get_value(key_group_fun, Options, fun(_,_) -> true end)
+    end.
+
+make_group_fun(Bt, exact) ->
+    fun({Key1, _}, {Key2, _}) ->
+        case less(Bt, {Key1, nil}, {Key2, nil}) of
+            false ->
+                case less(Bt, {Key2, nil}, {Key1, nil}) of
+                    false ->
+                        true;
+                    _ ->
+                        false
+                end;
+            _ ->
+                false
+        end
+    end;
+make_group_fun(Bt, GroupLevel) when is_integer(GroupLevel), GroupLevel > 0 ->
+    fun
+        ({[_|_] = Key1, _}, {[_|_] = Key2, _}) ->
+            SL1 = lists:sublist(Key1, GroupLevel),
+            SL2 = lists:sublist(Key2, GroupLevel),
+            case less(Bt, {SL1, nil}, {SL2, nil}) of
+                false ->
+                    case less(Bt, {SL2, nil}, {SL1, nil}) of
+                        false ->
+                            true;
+                        _ ->
+                            false
+                    end;
+                _ ->
+                    false
+            end;
+        ({Key1, _}, {Key2, _}) ->
+            case less(Bt, {Key1, nil}, {Key2, nil}) of
+                false ->
+                    case less(Bt, {Key2, nil}, {Key1, nil}) of
+                        false ->
+                            true;
+                        _ ->
+                            false
+                    end;
+                _ ->
+                    false
+            end
+    end.
+
 % wraps a 2 arity function with the proper 3 arity function
 convert_fun_arity(Fun) when is_function(Fun, 2) ->
     fun


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