Godeps/_workspace/src/gopkg.in/mgo.v2/session.go
func (c *Collection) Indexes() (indexes []Index, err error) {
	// Clone session and set it to Monotonic mode so that the server
	// used for the query may be safely obtained afterwards, if
	// necessary for iteration when a cursor is received.
	session := c.Database.Session
	cloned := session.Clone()
	cloned.SetMode(Monotonic, false)
	defer cloned.Close()

	batchSize := int(cloned.queryConfig.op.limit)

	// Try with a command.
	var result struct {
		Indexes []bson.Raw

		Cursor struct {
			FirstBatch []bson.Raw "firstBatch"
			NS         string
			Id         int64
		}
	}
	var iter *Iter
	err = c.Database.With(cloned).Run(bson.D{{"listIndexes", c.Name}, {"cursor", bson.D{{"batchSize", batchSize}}}}, &result)
	if err == nil {
		firstBatch := result.Indexes
		if firstBatch == nil {
			firstBatch = result.Cursor.FirstBatch
		}
		ns := strings.SplitN(result.Cursor.NS, ".", 2)
		if len(ns) < 2 {
			iter = c.With(cloned).NewIter(nil, firstBatch, result.Cursor.Id, nil)
		} else {
			iter = cloned.DB(ns[0]).C(ns[1]).NewIter(nil, firstBatch, result.Cursor.Id, nil)
		}
	} else if isNoCmd(err) {
		// Command not yet supported. Query the database instead.
		iter = c.Database.C("system.indexes").Find(bson.M{"ns": c.FullName}).Iter()
	} else {
		return nil, err
	}

	var spec indexSpec
	for iter.Next(&spec) {
		indexes = append(indexes, indexFromSpec(spec))
	}
	if err = iter.Close(); err != nil {
		return nil, err
	}
	sort.Sort(indexSlice(indexes))
	return indexes, nil
}
func (c *Collection) Indexes() (indexes []Index, err error) {
	// Clone session and set it to Monotonic mode so that the server
	// used for the query may be safely obtained afterwards, if
	// necessary for iteration when a cursor is received.
	session := c.Database.Session
	cloned := session.Clone()
	cloned.SetMode(Monotonic, false)
	defer cloned.Close()

	batchSize := int(cloned.queryConfig.op.limit)

	// Try with a command.
	var result struct {
		Indexes []bson.Raw

		Cursor struct {
			FirstBatch []bson.Raw "firstBatch"
			NS         string
			Id         int64
		}
	}
	var iter *Iter
	err = c.Database.With(cloned).Run(bson.D{{"listIndexes", c.Name}, {"cursor", bson.D{{"batchSize", batchSize}}}}, &result)
	if err == nil {
		firstBatch := result.Indexes
		if firstBatch == nil {
			firstBatch = result.Cursor.FirstBatch
		}
		ns := strings.SplitN(result.Cursor.NS, ".", 2)
		if len(ns) < 2 {
			iter = c.With(cloned).NewIter(nil, firstBatch, result.Cursor.Id, nil)
		} else {
			iter = cloned.DB(ns[0]).C(ns[1]).NewIter(nil, firstBatch, result.Cursor.Id, nil)
		}
	} else if isNoCmd(err) {
		// Command not yet supported. Query the database instead.
		iter = c.Database.C("system.indexes").Find(bson.M{"ns": c.FullName}).Iter()
	} else {
		return nil, err
	}

	var spec indexSpec
	for iter.Next(&spec) {
		indexes = append(indexes, indexFromSpec(spec))
	}
	if err = iter.Close(); err != nil {
		return nil, err
	}
	sort.Sort(indexSlice(indexes))
	return indexes, nil
}
// Indexes returns a list of all indexes for the collection.
//
// For example, this snippet would drop all available indexes:
//
//   indexes, err := collection.Indexes()
//   if err != nil {
//       return err
//   }
//   for _, index := range indexes {
//       err = collection.DropIndex(index.Key...)
//       if err != nil {
//           return err
//       }
//   }
//
// See the EnsureIndex method for more details on indexes.