pgj commented on code in PR #4662:
URL: https://github.com/apache/couchdb/pull/4662#discussion_r1306557440
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src/mango/src/mango_cursor.erl:
##########
@@ -44,27 +44,286 @@
-define(SUPERVISOR, mango_cursor_sup).
-create(Db, Selector0, Opts) ->
+-spec create(Db, Selector, Options, Kind) -> {ok, #cursor{}} when
+ Db :: database(),
+ Selector :: selector(),
+ Options :: cursor_options(),
+ Kind :: cursor_kind().
+create(Db, Selector0, Opts, Kind) ->
Selector = mango_selector:normalize(Selector0),
- UsableIndexes = mango_idx:get_usable_indexes(Db, Selector, Opts),
- case mango_cursor:maybe_filter_indexes_by_ddoc(UsableIndexes, Opts) of
+ {UsableIndexes, Trace} = mango_idx:get_usable_indexes(Db, Selector, Opts,
Kind),
+ case maybe_filter_indexes_by_ddoc(UsableIndexes, Opts) of
[] ->
% use_index doesn't match a valid index - fall back to a valid one
- create_cursor(Db, UsableIndexes, Selector, Opts);
+ create_cursor(Db, {UsableIndexes, Trace}, Selector, Opts);
UserSpecifiedIndex ->
- create_cursor(Db, UserSpecifiedIndex, Selector, Opts)
+ create_cursor(Db, {UserSpecifiedIndex, Trace}, Selector, Opts)
end.
+-spec enhance_candidates(Candidates, [{#idx{}, properties()}]) -> Candidates
when
+ Candidates :: #{#idx{} => properties()}.
+enhance_candidates(Entries, Inputs) ->
+ Combiner =
+ fun(Key, Value1, Value2) ->
+ case Key of
+ usable -> Value1 andalso Value2;
+ reason -> lists:append(Value1, Value2);
+ ranking -> Value1 + Value2
+ end
+ end,
+ lists:foldr(
+ fun({Index, Delta}, Map) ->
+ Updater = fun(Value) -> maps:merge_with(Combiner, Value, Delta)
end,
+ maps:update_with(Index, Updater, Map)
+ end,
+ Entries,
+ Inputs
+ ).
+
+-type ranking() :: pos_integer().
+-type properties() ::
+ #{
+ usable := boolean(),
+ ranking := ranking(),
+ reason := [reason()]
+ }.
+
+-spec tag_elems(properties(), sets:set(#idx{})) -> [{#idx{}, properties()}].
+tag_elems(Properties, Set) ->
+ sets:fold(fun(Index, Acc) -> [{Index, Properties} | Acc] end, [], Set).
+
+-type reason_description() ::
+ {name, reason()}.
+-type analysis_attribute() ::
+ {usable, boolean()}
+ | {reasons, [reason_description()]}
+ | {ranking, ranking()}
+ | {covering, boolean()}.
+-type analysis() ::
+ {[analysis_attribute()]}.
+-type candidate_index_attribute() ::
+ {index, #idx{}} | {analysis, analysis()}.
+-type candidate_index() ::
+ {[candidate_index_attribute()]}.
+
+-spec extract_candidate_indexes(#cursor{}) -> [candidate_index()].
+extract_candidate_indexes(Cursor) ->
+ #cursor{trace = Trace, index = Winner, fields = Fields} = Cursor,
+ #{
+ all_indexes := AllIndexes,
+ global_indexes := GlobalIndexes,
+ partition_indexes := PartitionIndexes,
+ usable_indexes := UsableIndexes,
+ usability_map := UsabilityMap,
+ filtered_indexes := FilteredIndexes,
+ indexes_of_type := IndexesOfType
+ } = Trace,
+ % specific to view indexes
+ SortedIndexRanges = maps:get(sorted_index_ranges, Trace, []),
+ % simple difference calculations to determine the results in each stage,
+ % without looking at the implementation
+ PartialIndexes = sets:subtract(AllIndexes, GlobalIndexes),
+ OutOfScopeIndexes = sets:subtract(GlobalIndexes, PartitionIndexes),
+ NotUsableIndexes = sets:subtract(PartitionIndexes, UsableIndexes),
+ ExcludedIndexes = sets:subtract(UsableIndexes, FilteredIndexes),
+ UnfavoredIndexes = sets:subtract(FilteredIndexes, IndexesOfType),
+ % determine rankings
+ UnfavoredIndexesRank = max(1, length(SortedIndexRanges)),
+ {_, [PartialIndexesRank, OutOfScopeIndexesRank, NotUsableIndexesRank,
ExcludedIndexesRank]} =
+ lists:foldl(
Review Comment:
Yeah, it makes sense. I will change it.
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