1 files changed, 63 insertions, 0 deletions
diff --git a/jstests/exists6.js b/jstests/exists6.js
new file mode 100644
index 0000000..7c1cdc1
--- /dev/null
+++ b/jstests/exists6.js
@@ -0,0 +1,63 @@
+// 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} );
+
+checkExists = function( query ) {
+    // Constraint on 'b' is trivial, so a BasicCursor is the default cursor type.
+    assert.eq( 'BasicCursor', t.find( query ).explain().cursor );
+    // Index bounds include all elements.
+    assert.eq( [ [ { $minElement:1 }, { $maxElement:1 } ] ], t.find( query ).hint( {b:1} ).explain().indexBounds.b );
+    // All keys must be scanned.
+    assert.eq( 3, t.find( query ).hint( {b:1} ).explain().nscanned );
+    // 2 docs will match.
+    assert.eq( 2, t.find( query ).hint( {b:1} ).itcount() );    
+}
+checkExists( {b:{$exists:true}} );
+checkExists( {b:{$not:{$exists:false}}} );
+
+checkMissing = function( query ) {
+    // Constraint on 'b' is nontrivial, so a BtreeCursor is the default cursor type.
+    assert.eq( 'BtreeCursor b_1', t.find( query ).explain().cursor );
+    // Scan null index keys.
+    assert.eq( [ [ null, null ] ], t.find( query ).explain().indexBounds.b );
+    // Two existing null keys will be scanned.
+    assert.eq( 2, t.find( query ).explain().nscanned );
+    // One doc is missing 'b'.
+    assert.eq( 1, t.find( query ).hint( {b:1} ).itcount() );    
+}
+checkMissing( {b:{$exists:false}} );
+checkMissing( {b:{$not:{$exists:true}}} );
+
+// 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} );
+
+checkExists = function( query ) {
+    // Index bounds include all elements.
+    assert.eq( [ [ { $minElement:1 }, { $maxElement:1 } ] ], t.find( query ).explain().indexBounds.b );
+    // All keys must be scanned.
+    assert.eq( 3, t.find( query ).explain().nscanned );
+    // 2 docs will match.
+    assert.eq( 2, t.find( query ).hint( {a:1,b:1} ).itcount() );    
+}
+checkExists( {a:1,b:{$exists:true}} );
+checkExists( {a:1,b:{$not:{$exists:false}}} );
+
+checkMissing = function( query ) {
+    // Scan null index keys.
+    assert.eq( [ [ null, null ] ], t.find( query ).explain().indexBounds.b );
+    // Two existing null keys will be scanned.
+    assert.eq( 2, t.find( query ).explain().nscanned );
+    // One doc is missing 'b'.
+    assert.eq( 1, t.find( query ).hint( {a:1,b:1} ).itcount() );    
+}
+checkMissing( {a:1,b:{$exists:false}} );
+checkMissing( {a:1,b:{$not:{$exists:true}}} );