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Posted to commits@couchdb.apache.org by wi...@apache.org on 2017/09/12 12:06:44 UTC
[couchdb] 01/02: Avoid duplicate index selection in Mango
This is an automated email from the ASF dual-hosted git repository.
willholley pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/couchdb.git
commit 04e4cfa0c670c89324887d9c1c28139cca65a230
Author: Will Holley <wi...@gmail.com>
AuthorDate: Tue Sep 12 07:55:44 2017 +0100
Avoid duplicate index selection in Mango
Previously, index selection for a given query
was run twice for each request - once to add
a warning in case a full database scan would be
performed and then again when the query was executed.
This moves the warning generation so that it occurs
at the end of the query processing and we can use
the existing index context to decide whether to
add a warning or not.
Whilst only a minor optimisation (which also assumes
we don't have cached query plans etc), it
at least moves index selection to where you'd expect
it to happen (query planning).
---
src/mango/src/mango_cursor.erl | 15 ++++++++++++++-
src/mango/src/mango_cursor_text.erl | 3 ++-
src/mango/src/mango_cursor_view.erl | 3 ++-
src/mango/src/mango_httpd.erl | 16 +++-------------
src/mango/test/12-use-correct-index.py | 7 +++++++
5 files changed, 28 insertions(+), 16 deletions(-)
diff --git a/src/mango/src/mango_cursor.erl b/src/mango/src/mango_cursor.erl
index cf71790..12ce2c9 100644
--- a/src/mango/src/mango_cursor.erl
+++ b/src/mango/src/mango_cursor.erl
@@ -17,13 +17,15 @@
create/3,
explain/1,
execute/3,
- maybe_filter_indexes/2
+ maybe_filter_indexes/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).
@@ -134,3 +136,14 @@ group_indexes_by_type(Indexes) ->
[]
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.
\ No newline at end of file
diff --git a/src/mango/src/mango_cursor_text.erl b/src/mango/src/mango_cursor_text.erl
index ea62cd6..70c911a 100644
--- a/src/mango/src/mango_cursor_text.erl
+++ b/src/mango/src/mango_cursor_text.erl
@@ -124,7 +124,8 @@ execute(Cursor, UserFun, UserAcc) ->
Arg = {add_key, bookmark, JsonBM},
{_Go, FinalUserAcc} = UserFun(Arg, LastUserAcc),
FinalUserAcc0 = mango_execution_stats:maybe_add_stats(Opts, UserFun, Stats0, FinalUserAcc),
- {ok, FinalUserAcc0}
+ FinalUserAcc1 = mango_cursor:maybe_add_warning(UserFun, Idx, FinalUserAcc0),
+ {ok, FinalUserAcc1}
end.
diff --git a/src/mango/src/mango_cursor_view.erl b/src/mango/src/mango_cursor_view.erl
index b292704..31e198f 100644
--- a/src/mango/src/mango_cursor_view.erl
+++ b/src/mango/src/mango_cursor_view.erl
@@ -118,7 +118,8 @@ execute(#cursor{db = Db, index = Idx, execution_stats = Stats} = Cursor0, UserFu
{_Go, FinalUserAcc} = UserFun(Arg, LastCursor#cursor.user_acc),
Stats0 = LastCursor#cursor.execution_stats,
FinalUserAcc0 = mango_execution_stats:maybe_add_stats(Opts, UserFun, Stats0, FinalUserAcc),
- {ok, FinalUserAcc0};
+ FinalUserAcc1 = mango_cursor:maybe_add_warning(UserFun, Idx, FinalUserAcc0),
+ {ok, FinalUserAcc1};
{error, Reason} ->
{error, Reason}
end
diff --git a/src/mango/src/mango_httpd.erl b/src/mango/src/mango_httpd.erl
index a99b054..33e0c1c 100644
--- a/src/mango/src/mango_httpd.erl
+++ b/src/mango/src/mango_httpd.erl
@@ -183,7 +183,7 @@ handle_find_req(#httpd{method='POST'}=Req, Db) ->
chttpd:validate_ctype(Req, "application/json"),
{ok, Opts0} = mango_opts:validate_find(chttpd:json_body_obj(Req)),
{value, {selector, Sel}, Opts} = lists:keytake(selector, 1, Opts0),
- {ok, Resp0} = start_find_resp(Req, Db, Sel, Opts),
+ {ok, Resp0} = start_find_resp(Req),
{ok, AccOut} = run_find(Resp0, Db, Sel, Opts),
end_find_resp(AccOut);
@@ -230,18 +230,8 @@ convert_to_design_id(DDocId) ->
end.
-start_find_resp(Req, Db, Sel, Opts) ->
- chttpd:start_delayed_json_response(Req, 200, [], maybe_add_warning(Db, Sel, Opts)).
-
-
-maybe_add_warning(Db, Selector, Opts) ->
- UsableIndexes = mango_idx:get_usable_indexes(Db, Selector, Opts),
- case length(UsableIndexes) of
- 0 ->
- "{\"warning\":\"no matching index found, create an index to optimize query time\",\r\n\"docs\":[";
- _ ->
- "{\"docs\":["
- end.
+start_find_resp(Req) ->
+ chttpd:start_delayed_json_response(Req, 200, [], "{\"docs\":[").
end_find_resp(Acc0) ->
diff --git a/src/mango/test/12-use-correct-index.py b/src/mango/test/12-use-correct-index.py
index f1eaf5f..aaa7980 100644
--- a/src/mango/test/12-use-correct-index.py
+++ b/src/mango/test/12-use-correct-index.py
@@ -88,6 +88,13 @@ class ChooseCorrectIndexForDocs(mango.DbPerClass):
explain = self.db.find({"name": "Eddie", "number": {"$lte": 12}}, explain=True)
assert explain["index"]["ddoc"] == '_design/zzz'
+ def test_warn_on_full_db_scan(self):
+ selector = {"not_indexed":"foo"}
+ explain_resp = self.db.find(selector, explain=True, return_raw=True)
+ assert explain_resp["index"]["type"] == "special"
+ resp = self.db.find(selector, return_raw=True)
+ assert resp["warning"] == "no matching index found, create an index to optimize query time"
+
def test_chooses_idxA(self):
DOCS2 = [
{"a":1, "b":1, "c":1},
--
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