Post index update

The good:

We were able to delete more indexes than we added. 4 deleted, 3 added.

The bad:

The indexes that we added takes up more RAM than the ones removed. To add to that, the `delete_spam` index had a size of 0 which does not really improve performance at all.

db.contents.stats(1024*1024)

{
"ns" : "comments-prod.contents",
"count" : 7567251,
"size" : 5808,
"avgObjSize" : 804,
"storageSize" : 6624,
"numExtents" : 29,
"nindexes" : 23,
"lastExtentSize" : 511,
"paddingFactor" : 1,
"systemFlags" : 1,
"userFlags" : 0,
"totalIndexSize" : 11907,
"indexSizes" : {
"_id_" : 328,
"parent_id_1" : 269,
"parent_ids_1" : 278,
"tags_array_1" : 253,
"author_id_1_course_id_1" : 494,
"votes.up_1__type_1" : 475,
"votes.down_1__type_1" : 467,
"commentable_id_1_created_at_-1" : 461,
"course_id_1__type_1_created_at_-1" : 736,
"_type_1_comment_thread_id_1_author_id_1_updated_at_1" : 489,
"comment_thread_id_1_sk_1" : 301,
"comment_thread_id_1_endorsed_1" : 142,
"_type_1_course_id_1_pinned_-1_created_at_-1" : 751,
"_type_1_course_id_1_pinned_-1_comment_count_-1_created_at_-1" : 793,
"_type_1_course_id_1_pinned_-1_votes.point_-1_created_at_-1" : 851,
"commentable_id_1" : 190,
"_type_1_course_id_1_context_1_pinned_-1_created_at_-1" : 709,
"_type_1_context_1" : 348,
"_type_-1_course_id_1_context_1_pinned_-1_last_activity_at_-1_created_at_-1" : 701,
"_type_-1_course_id_1_commentable_id_1_context_1_pinned_-1_created_at_-1" : 780,
"_type_-1_course_id_1_endorsed_-1_pinned_-1_last_activity_at_-1_created_at_-1" : 677,
"_type_-1_course_id_1_endorsed_-1_pinned_-1_votes.point_-1_created_at_-1" : 725,
"_type_-1_course_id_1_endorsed_-1_pinned_-1_comment_count_-1_created_at_-1" : 679
},
"ok" : 1
}