1 files changed, 41 insertions, 0 deletions
diff --git a/jstests/indexn.js b/jstests/indexn.js
new file mode 100644
index 0000000..d5800e4
--- /dev/null
+++ b/jstests/indexn.js
@@ -0,0 +1,41 @@
+// Check fast detection of empty result set with a single key index SERVER-958.
+
+t = db.jstests_indexn;
+t.drop();
+
+function checkImpossibleMatchDummyCursor( explain ) {
+    assert.eq( 'BasicCursor', explain.cursor );
+    assert.eq( 0, explain.nscanned );
+    assert.eq( 0, explain.n );
+}
+
+t.save( {a:1,b:[1,2]} );
+
+t.ensureIndex( {a:1} );
+t.ensureIndex( {b:1} );
+
+assert.eq( 0, t.count( {a:{$gt:5,$lt:0}} ) );
+// {a:1} is a single key index, so no matches are possible for this query
+checkImpossibleMatchDummyCursor( t.find( {a:{$gt:5,$lt:0}} ).explain() );
+
+assert.eq( 0, t.count( {a:{$gt:5,$lt:0},b:2} ) );
+checkImpossibleMatchDummyCursor( t.find( {a:{$gt:5,$lt:0},b:2} ).explain() );
+
+assert.eq( 0, t.count( {a:{$gt:5,$lt:0},b:{$gt:0,$lt:5}} ) );
+checkImpossibleMatchDummyCursor( t.find( {a:{$gt:5,$lt:0},b:{$gt:0,$lt:5}} ).explain() );
+
+assert.eq( 1, t.count( {$or:[{a:{$gt:5,$lt:0}},{a:1}]} ) );
+checkImpossibleMatchDummyCursor( t.find( {$or:[{a:{$gt:5,$lt:0}},{a:1}]} ).explain().clauses[ 0 ] );
+
+// A following invalid range is eliminated.
+assert.eq( 1, t.count( {$or:[{a:1},{a:{$gt:5,$lt:0}}]} ) );
+assert.eq( null, t.find( {$or:[{a:1},{a:{$gt:5,$lt:0}}]} ).explain().clauses );
+
+t.save( {a:2} );
+
+// An intermediate invalid range is eliminated.
+assert.eq( 2, t.count( {$or:[{a:1},{a:{$gt:5,$lt:0}},{a:2}]} ) );
+explain = t.find( {$or:[{a:1},{a:{$gt:5,$lt:0}},{a:2}]} ).explain();
+assert.eq( 2, explain.clauses.length );
+assert.eq( [[1,1]], explain.clauses[ 0 ].indexBounds.a );
+assert.eq( [[2,2]], explain.clauses[ 1 ].indexBounds.a );