1 files changed, 79 insertions, 0 deletions
diff --git a/jstests/core/exists6.js b/jstests/core/exists6.js
new file mode 100644
index 00000000000..2fa4ba85d49
--- /dev/null
+++ b/jstests/core/exists6.js
@@ -0,0 +1,79 @@
+// SERVER-393 Test indexed matching with $exists.
+
+t = db.jstests_exists6;
+t.drop();
+
+t.ensureIndex( {b:1} );
+t.save( {} );
+t.save( {b:1} );
+t.save( {b:null} );
+
+//---------------------------------
+
+function checkIndexUse( query, usesIndex, index, bounds ) {
+    var x = t.find( query ).explain()
+    if ( usesIndex ) {
+        assert.eq( x.cursor.indexOf(index), 0 , tojson(x) );
+        if ( ! x.indexBounds ) x.indexBounds = {}
+        assert.eq( bounds, x.indexBounds.b , tojson(x) );
+    }
+    else {
+        assert.eq( 'BasicCursor', x.cursor, tojson(x) );
+    }
+}
+
+function checkExists( query, usesIndex, bounds ) {
+    checkIndexUse( query, usesIndex, 'BtreeCursor b_1', bounds );
+    // Whether we use an index or not, we will always scan all docs.
+    assert.eq( 3, t.find( query ).explain().nscanned );
+    // 2 docs will match.
+    assert.eq( 2, t.find( query ).itcount() );
+}
+
+function checkMissing( query, usesIndex, bounds ) {
+    checkIndexUse( query, usesIndex, 'BtreeCursor b_1', bounds );
+    // Nscanned changes based on index usage.
+    if ( usesIndex ) assert.eq( 2, t.find( query ).explain().nscanned );
+    else assert.eq( 3, t.find( query ).explain().nscanned );
+    // 1 doc is missing 'b'.
+    assert.eq( 1, t.find( query ).itcount() );
+}
+
+function checkExistsCompound( query, usesIndex, bounds ) {
+    checkIndexUse( query, usesIndex, 'BtreeCursor', bounds );
+    if ( usesIndex ) assert.eq( 3, t.find( query ).explain().nscanned );
+    else assert.eq( 3, t.find( query ).explain().nscanned );
+    // 2 docs have a:1 and b:exists.
+    assert.eq( 2, t.find( query ).itcount() );
+}
+
+function checkMissingCompound( query, usesIndex, bounds ) {
+    checkIndexUse( query, usesIndex, 'BtreeCursor', bounds );
+    // two possible indexes to use
+    // 1 doc should match
+    assert.eq( 1, t.find( query ).itcount() );
+}
+
+//---------------------------------
+
+var allValues = [ [ { $minElement:1 }, { $maxElement:1 } ] ];
+var nullNull = [ [ null, null ] ];
+
+// Basic cases
+checkExists( {b:{$exists:true}}, true, allValues );
+// We change this to not -> not -> exists:true, and get allValue for bounds
+// but we use a BasicCursor?
+checkExists( {b:{$not:{$exists:false}}}, false, allValues );
+checkMissing( {b:{$exists:false}}, true, nullNull );
+checkMissing( {b:{$not:{$exists:true}}}, true, nullNull );
+
+// Now check existence of second compound field.
+t.ensureIndex( {a:1,b:1} );
+t.save( {a:1} );
+t.save( {a:1,b:1} );
+t.save( {a:1,b:null} );
+
+checkExistsCompound( {a:1,b:{$exists:true}}, true, allValues );
+checkExistsCompound( {a:1,b:{$not:{$exists:false}}}, true, allValues );
+checkMissingCompound( {a:1,b:{$exists:false}}, true, nullNull );
+checkMissingCompound( {a:1,b:{$not:{$exists:true}}}, true, nullNull );