MongoDB Sharding 101

1 .

2 .

3 .● ● ● ● ● 

4 .● ● ● 

5 .● ● 

6 .● ● ● ● 

7 . PRIMARY Secondary Secondary 

8 .Secondaries - Pull oplog and apply locally 

9 .● ● ● ● ● 

10 . Chained replication Secondaries - Pull oplog and apply locally 

11 .Delayed Secondary Secondaries - Pull oplog and apply locally 

12 .

13 .

14 .● 

15 .

16 .

17 . Config Servers mongos Shard1 Shard2 

18 .

19 . shard1 shard2 A database can have multiple collections, each collection can be sharded differently. Each shard has chunks and their documents. 

20 .

21 .● ● ● 

22 .

23 .

24 .

25 .

26 .

27 .

28 . Config Servers mongos Shard1 Shard2 

29 .● ● ● ● ●