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The following commit(s) were added to refs/heads/master by this push:
new 7c37e58 Mango: change catch-all field range priority (#1069)
7c37e58 is described below
commit 7c37e5863905185902f2e07dc8ce0d3019df34e4
Author: Will Holley <[email protected]>
AuthorDate: Tue Dec 19 13:04:44 2017 +0000
Mango: change catch-all field range priority (#1069)
01252f97 introduced a "catch-all" feature to Mango that allowed
queries to fall back on a full database scan (_all_docs) when
no valid index was available.
This worked by creating a special index range representing
the full database scan.
For example, a selector:
{ "_id": "foo" }
would be translated into a field range of:
[{ "startkey": "foo", "endkey": "foo"}]
then prepending the catch-all field range, we would have:
[
{ "startkey": null, "endkey": max_json_value},
{ "startkey": "foo", "endkey": "foo"}
]
This set gets passed into
mango_cursor_view:choose_best_index to determine most selective
index and field range combination to use. Unfortunately, in
the event that we have one possible index (all_docs) and multiple
valid ranges, it just chooses the first range it finds -
the full index scan in this case.
This commit makes the catch-all field range the last
available option, ensuring we use the more selective
range where available.
---
src/mango/src/mango_cursor_special.erl | 7 +++++--
src/mango/test/03-operator-test.py | 9 ++++++++-
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/src/mango/src/mango_cursor_special.erl
b/src/mango/src/mango_cursor_special.erl
index 78cac7f..f4a760d 100644
--- a/src/mango/src/mango_cursor_special.erl
+++ b/src/mango/src/mango_cursor_special.erl
@@ -31,10 +31,13 @@
create(Db, Indexes, Selector, Opts) ->
InitialRange = mango_idx_view:field_ranges(Selector),
CatchAll = [{<<"_id">>, {'$gt', null, '$lt', mango_json_max}}],
- FieldRanges = lists:append(CatchAll, InitialRange),
+ % order matters here - we only want to use the catchall index
+ % if no other range can fulfill the query (because we know)
+ % catchall is the most expensive range
+ FieldRanges = InitialRange ++ CatchAll,
Composited = mango_cursor_view:composite_indexes(Indexes, FieldRanges),
{Index, IndexRanges} = mango_cursor_view:choose_best_index(Db, Composited),
-
+
Limit = couch_util:get_value(limit, Opts, mango_opts:default_limit()),
Skip = couch_util:get_value(skip, Opts, 0),
Fields = couch_util:get_value(fields, Opts, all_fields),
diff --git a/src/mango/test/03-operator-test.py
b/src/mango/test/03-operator-test.py
index 239cc7d..4650c7e 100644
--- a/src/mango/test/03-operator-test.py
+++ b/src/mango/test/03-operator-test.py
@@ -264,6 +264,13 @@ class OperatorTextTests(mango.UserDocsTextTests,
OperatorTests):
class OperatorAllDocsTests(mango.UserDocsTestsNoIndexes, OperatorTests):
- pass
+ def test_range_id_eq(self):
+ doc_id = "8e1c90c0-ac18-4832-8081-40d14325bde0"
+ r = self.db.find({
+ "_id": doc_id
+ }, explain=True, return_raw=True)
+
+ self.assertEqual(r["mrargs"]["end_key"], doc_id)
+ self.assertEqual(r["mrargs"]["start_key"], doc_id)
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