18. http://www.mongodb.org/display/DOCS/Replica+Sets+-+Oplog

19. myset:PRIMARY> db.mycoll.insert({x:1})
myset:PRIMARY> db.mycoll.update({x:1}, {$set : {y:1}})
myset:PRIMARY> db.mycoll.update({x:2}, {$set : {y:1}}, true)
myset:PRIMARY> db.mycoll.remove({x:1})
myset:PRIMARY> db.mycoll.find()
{ "_id" : ObjectId("4def8e5fb07da951204c60e0"), "x" : 1, "y" : 1 }
{ "_id" : ObjectId("4def8e5fd60f868d9ea77776"), "x" : 2, "y" : 1 }

20. myset:PRIMARY> use local
myset:PRIMARY> db.oplog.rs.find().sort({$natural:-1})
{ "ts" : { "t" : 1307545183000, "i" : 4 }, "h" : NumberLong("-1214445074120755058"), "op" : "d",
"ns" : "test.mycoll", "b" : true, "o" : { "_id" : ObjectId("4def8e5fb07da951204c60e0") } }
{ "ts" : { "t" : 1307545183000, "i" : 3 }, "h" : NumberLong("296197708926251535"), "op" : "i",
"ns" : "test.mycoll", "o" : { "_id" : ObjectId("4def8e5fd60f868d9ea77776"), "x" : 2, "y" : 1 } }
{ "ts" : { "t" : 1307545183000, "i" : 2 }, "h" : NumberLong("6923456793495821492"), "op" : "u",
"ns" : "test.mycoll", "o2" : { "_id" : ObjectId("4def8e5fb07da951204c60e0") }, "o" : { "$set" :
{ "y" : 1 } } }
{ "ts" : { "t" : 1307545183000, "i" : 1 }, "h" : NumberLong("-4148240362977057242"), "op" : "i",
"ns" : "test.mycoll", "o" : { "_id" : ObjectId("4def8e5fb07da951204c60e0"), "x" : 1 } }
...

21. Wed Jun 8 23:53:38 [conn6] getmore local.oplog.rs cid:3687673685314762755 getMore:
{ ts: { $gte: new Date(5615858237044687812) } } bytes:20 nreturned:0 3022ms
Wed Jun 8 23:53:38 [conn8] getmore local.oplog.rs cid:9178181051262829411 getMore:
{ ts: { $gte: new Date(5615858237044687812) } } bytes:20 nreturned:0 3046ms
Wed Jun 8 23:53:41 [conn8] getmore local.oplog.rs cid:9178181051262829411 getMore:
{ ts: { $gte: new Date(5615858237044687812) } } bytes:20 nreturned:0 3041ms
Wed Jun 8 23:53:41 [conn6] getmore local.oplog.rs cid:3687673685314762755 getMore:
{ ts: { $gte: new Date(5615858237044687812) } } bytes:20 nreturned:0 3043ms
...

22. myset:SECONDARY> db.oplog.rs.find().sort({$natural:-1})
{ "ts" : { "t" : 1307545183000, "i" : 4 }, "h" : NumberLong("-1214445074120755058"), "op" : "d",
"ns" : "test.mycoll", "b" : true, "o" : { "_id" : ObjectId("4def8e5fb07da951204c60e0") } }
{ "ts" : { "t" : 1307545183000, "i" : 3 }, "h" : NumberLong("296197708926251535"), "op" : "i",
"ns" : "test.mycoll", "o" : { "_id" : ObjectId("4def8e5fd60f868d9ea77776"), "x" : 2, "y" : 1 } }
{ "ts" : { "t" : 1307545183000, "i" : 2 }, "h" : NumberLong("6923456793495821492"), "op" : "u",
"ns" : "test.mycoll", "o2" : { "_id" : ObjectId("4def8e5fb07da951204c60e0") }, "o" : { "$set" :
{ "y" : 1 } } }
{ "ts" : { "t" : 1307545183000, "i" : 1 }, "h" : NumberLong("-4148240362977057242"), "op" : "i",
"ns" : "test.mycoll", "o" : { "_id" : ObjectId("4def8e5fb07da951204c60e0"), "x" : 1 } }
...