t = db.find6;
t.drop();

t.save( { a : 1 } )
t.save( { a : 1 , b : 1 } )

assert.eq( 2 , t.find().count() , "A" );
assert.eq( 1 , t.find( { b : null } ).count() , "B" );
assert.eq( 1 , t.find( "function() { return this.b == null; }" ).itcount() , "C" );
assert.eq( 1 , t.find( "function() { return this.b == null; }" ).count() , "D" );

/* test some stuff with dot array notation */
q = db.find6a;
q.drop();
q.insert( { "a" : [ { "0" : 1 } ] } );
q.insert( { "a" : [ { "0" : 2 } ] } );
q.insert( { "a" : [ 1 ] } );
q.insert( { "a" : [ 9, 1 ] } );

function f() { 

    assert.eq( 2, q.find( { 'a.0' : 1 } ).count(), "da1");
    assert.eq( 2, q.find( { 'a.0' : 1 } ).count(), "da2");
    
    assert.eq( 1, q.find( { 'a.0' : { $gt : 8 } } ).count(), "da3");
    assert.eq( 0, q.find( { 'a.0' : { $lt : 0 } } ).count(), "da4");

}

for( var pass = 0; pass <= 1 ; pass++ ) { 
    f();
    q.ensureIndex({a:1});
}

t = db.multidim;
t.drop();
t.insert({"a" : [ [ ], 1, [ 3, 4 ] ] });
assert.eq(1, t.find({"a.2":[3,4]}).count(), "md1");
assert.eq(1, t.find({"a.2.1":4}).count(), "md2");
assert.eq(0, t.find({"a.2.1":3}).count(), "md3");