1 files changed, 85 insertions, 0 deletions
diff --git a/jstests/core/idhack.js b/jstests/core/idhack.js
new file mode 100644
index 00000000000..11fb1e0f447
--- /dev/null
+++ b/jstests/core/idhack.js
@@ -0,0 +1,85 @@
+
+t = db.idhack
+t.drop()
+
+
+t.insert( { _id : { x : 1 } , z : 1 } )
+t.insert( { _id : { x : 2 } , z : 2 } )
+t.insert( { _id : { x : 3 } , z : 3 } )
+t.insert( { _id : 1 , z : 4 } )
+t.insert( { _id : 2 , z : 5 } )
+t.insert( { _id : 3 , z : 6 } )
+
+assert.eq( 2 , t.findOne( { _id : { x : 2 } } ).z , "A1" )
+assert.eq( 2 , t.find( { _id : { $gte : 2 } } ).count() , "A2" )
+assert.eq( 2 , t.find( { _id : { $gte : 2 } } ).itcount() , "A3" )
+
+t.update( { _id : { x : 2 } } , { $set : { z : 7 } } )
+assert.eq( 7 , t.findOne( { _id : { x : 2 } } ).z , "B1" )
+
+t.update( { _id : { $gte : 2 } } , { $set : { z : 8 } } , false , true )
+assert.eq( 4 , t.findOne( { _id : 1 } ).z , "C1" )
+assert.eq( 8 , t.findOne( { _id : 2 } ).z , "C2" )
+assert.eq( 8 , t.findOne( { _id : 3 } ).z , "C3" )
+
+// explain output should show that the ID hack was applied.
+var query = { _id : { x : 2 } };
+var explain = t.find( query ).explain( true );
+print( "explain for " + tojson( query , "" , true ) + " = " + tojson( explain ) );
+assert.eq( 1 , explain.n , "D1" );
+assert.eq( 1 , explain.nscanned , "D2" );
+assert.neq( undefined , explain.cursor , "D3" );
+assert.neq( "" , explain.cursor , "D4" );
+assert.neq( undefined , explain.indexBounds , "D5" );
+assert.neq( {} , explain.indexBounds , "D6" );
+
+// ID hack cannot be used with hint().
+var query = { _id : { x : 2 } };
+var explain = t.find( query ).explain();
+t.ensureIndex( { _id : 1 , a : 1 } );
+var hintExplain = t.find( query ).hint( { _id : 1 , a : 1 } ).explain();
+print( "explain for hinted query = " + tojson( hintExplain ) );
+assert.neq( explain.cursor, hintExplain.cursor, "E1" );
+
+// ID hack cannot be used with skip().
+var skipExplain = t.find( query ).skip(1).explain();
+print( "explain for skip query = " + tojson( skipExplain ) );
+assert.neq( explain.cursor, skipExplain.cursor, "F1" );
+
+// Covered query returning _id field only can be handled by ID hack.
+var coveredExplain = t.find( query, { _id : 1 } ).explain();
+print( "explain for covered query = " + tojson( coveredExplain ) );
+assert.eq( explain.cursor, coveredExplain.cursor, "G1" );
+// Check doc from covered ID hack query.
+assert.eq( { _id : { x: 2 } }, t.findOne( query, { _id : 1 } ), "G2" );
+
+//
+// Non-covered projection for idhack.
+//
+
+t.drop();
+t.insert( { _id: 0, a: 0, b: [ { c: 1 }, { c: 2 } ] });
+t.insert( { _id: 1, a: 1, b: [ { c: 3 }, { c: 4 } ] });
+
+// Simple inclusion.
+assert.eq( { _id: 1, a: 1 }, t.find( { _id: 1 }, { a: 1 } ).next() );
+assert.eq( { a: 1 }, t.find({ _id: 1 }, { _id: 0, a: 1 } ).next() );
+assert.eq( { _id: 0, a: 0 }, t.find( { _id: 0 }, { _id: 1, a: 1 } ).next() );
+
+// Non-simple: exclusion.
+assert.eq( { _id: 1, a: 1 }, t.find( { _id: 1 }, { b: 0 } ).next() );
+assert.eq( { _id: 0, }, t.find( { _id: 0 }, { a: 0, b: 0 } ).next() );
+
+// Non-simple: dotted fields.
+assert.eq( { b: [ { c: 1 }, { c: 2 } ] }, t.find( { _id: 0 }, { _id: 0, "b.c": 1 } ).next() );
+assert.eq( { _id: 1 }, t.find( { _id: 1 }, { "foo.bar": 1 } ).next() );
+
+// Non-simple: elemMatch projection.
+assert.eq( { _id: 1, b: [ { c: 4 } ] },
+           t.find( { _id: 1 }, { b: { $elemMatch: { c: 4 } } } ).next() );
+
+// Non-simple: $returnKey.
+assert.eq( { _id: 1 }, t.find( { _id: 1 } )._addSpecial( "$returnKey", true ).next() );
+
+// Non-simple: $returnKey overrides other projections.
+assert.eq( { _id: 1 }, t.find( { _id: 1 }, { a: 1 } )._addSpecial( "$returnKey", true ).next() );