Mongodb limits
項目 Limits
BSONDocument MAX 16M (在同一個
Collection ,一份Document
Record 最大是16M,但可以有
多份 Documents)
Namespace Length
database and collection
nam
MAX 123 Bytes
Replica Sets
voting member
Max 12 members
7members in same time
Sharding and replicate
Sharding 及Replicate set
Replicate 可以再加上一層Sharding 切片將資
料放至另一個Replicate sets ,
可以將Replicate set 改成 Sharding cluster
也可以將Sharding convert 成 replicate
(不建議作,因為會有Data loss 風險)
14.
Sharding
將資料分散儲存在多台機器的機制
Clustersharding 需大量的記憶體 及1台
config serve 存放 META DATA
在作Sharding 時會將資料都放在RAM 中,以
求減尐page out 的機率
run a query that requires MongoDB to scan every document in
a collection, the working set includes every active document in
memory.
參考文件
Is MongoDBa good alternative to RDBMs
databases (like Oracle and Mysql)
22.
Concepts
1.sharding justcute date to slice and save
to different machines. Also sharding is
auto do
2.replicates is keep data have same copy
3.security option default is close, mean
everyone can login to MongoDB.