1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(mango_cursor).
-export([
create/3,
explain/1,
execute/3,
maybe_filter_indexes_by_ddoc/2,
maybe_add_warning/3
]).
-include_lib("couch/include/couch_db.hrl").
-include("mango.hrl").
-include("mango_cursor.hrl").
-include("mango_idx.hrl").
-ifdef(HAVE_DREYFUS).
-define(CURSOR_MODULES, [
mango_cursor_view,
mango_cursor_text,
mango_cursor_special
]).
-else.
-define(CURSOR_MODULES, [
mango_cursor_view,
mango_cursor_special
]).
-endif.
-define(SUPERVISOR, mango_cursor_sup).
create(Db, Selector0, Opts) ->
Selector = mango_selector:normalize(Selector0),
UsableIndexes = mango_idx:get_usable_indexes(Db, Selector0, Opts),
{use_index, IndexSpecified} = proplists:lookup(use_index, Opts),
case {length(UsableIndexes), length(IndexSpecified)} of
{0, 1} ->
?MANGO_ERROR({no_usable_index, selector_unsupported});
{0, 0} ->
AllDocs = mango_idx:special(Db),
create_cursor(Db, AllDocs, Selector, Opts);
_ ->
create_cursor(Db, UsableIndexes, Selector, Opts)
end.
explain(#cursor{}=Cursor) ->
#cursor{
index = Idx,
selector = Selector,
opts = Opts0,
limit = Limit,
skip = Skip,
fields = Fields
} = Cursor,
Mod = mango_idx:cursor_mod(Idx),
Opts = lists:keydelete(user_ctx, 1, Opts0),
{[
{dbname, mango_idx:dbname(Idx)},
{index, mango_idx:to_json(Idx)},
{selector, Selector},
{opts, {Opts}},
{limit, Limit},
{skip, Skip},
{fields, Fields}
] ++ Mod:explain(Cursor)}.
execute(#cursor{index=Idx}=Cursor, UserFun, UserAcc) ->
Mod = mango_idx:cursor_mod(Idx),
Mod:execute(Cursor, UserFun, UserAcc).
maybe_filter_indexes_by_ddoc(Indexes, Opts) ->
case lists:keyfind(use_index, 1, Opts) of
{use_index, []} ->
% We remove any indexes that have a selector
% since they are only used when specified via use_index
remove_indexes_with_partial_filter_selector(Indexes);
{use_index, [DesignId]} ->
filter_indexes(Indexes, DesignId);
{use_index, [DesignId, ViewName]} ->
filter_indexes(Indexes, DesignId, ViewName)
end.
filter_indexes(Indexes, DesignId0) ->
DesignId = case DesignId0 of
<<"_design/", _/binary>> ->
DesignId0;
Else ->
<<"_design/", Else/binary>>
end,
FiltFun = fun(I) -> mango_idx:ddoc(I) == DesignId end,
lists:filter(FiltFun, Indexes).
filter_indexes(Indexes0, DesignId, ViewName) ->
Indexes = filter_indexes(Indexes0, DesignId),
FiltFun = fun(I) -> mango_idx:name(I) == ViewName end,
lists:filter(FiltFun, Indexes).
remove_indexes_with_partial_filter_selector(Indexes) ->
FiltFun = fun(Idx) ->
case mango_idx:get_partial_filter_selector(Idx) of
undefined -> true;
_ -> false
end
end,
lists:filter(FiltFun, Indexes).
create_cursor(Db, Indexes, Selector, Opts) ->
[{CursorMod, CursorModIndexes} | _] = group_indexes_by_type(Indexes),
CursorMod:create(Db, CursorModIndexes, Selector, Opts).
group_indexes_by_type(Indexes) ->
IdxDict = lists:foldl(fun(I, D) ->
dict:append(mango_idx:cursor_mod(I), I, D)
end, dict:new(), Indexes),
% The first cursor module that has indexes will be
% used to service this query. This is so that we
% don't suddenly switch indexes for existing client
% queries.
lists:flatmap(fun(CMod) ->
case dict:find(CMod, IdxDict) of
{ok, CModIndexes} ->
[{CMod, CModIndexes}];
error ->
[]
end
end, ?CURSOR_MODULES).
maybe_add_warning(UserFun, #idx{type = IndexType}, UserAcc) ->
case IndexType of
<<"special">> ->
Arg = {add_key, warning, <<"no matching index found, create an index to optimize query time">>},
{_Go, UserAcc0} = UserFun(Arg, UserAcc),
UserAcc0;
_ ->
UserAcc
end.
|
