mongo/jstests/core/queryoptimizer6.js

// Test that $ne constraints are accounted for in QueryPattern. SERVER-4665

t = db.jstests_queryoptimizer6;
t.drop();

t.save({a: 1});

// There is a bug in the 2.4.x indexing where the first query below returns 0 results with this
// index, but 1 result without it.
//
// t.ensureIndex( {b:1}, {sparse:true} );

// The sparse index will be used, and recorded for this query pattern.
assert.eq(1, t.find({a: 1, b: {$ne: 1}}).itcount());
// The query pattern should be different, and the sparse index should not be used.
assert.eq(1, t.find({a: 1}).itcount());