CODEWITHSUNDEEP
mongodbsharding
Adithya Visnu
Adithya Visnu

Reputation: 12

shardcollection with existing document mongodb

Let's say that I had a collection called "History" and "Employees" and there will a document on it.

When I create first collection with 

sh.shardCollection("Databases.History",{"email":1})

it works fine, and I add some document on it.

But. When I create the second collections named "Employees" with 

db.Employees.insert({"name":"Jhon Wick", "email":"[email protected]"})

and create a shard collections on it with 

sh.shardCollection("Databases.Employees",{"email":1})

, it doesn't work.

MongoDB says that "please create an index that starts with the shard key before sharding."

so I tried add some index to Employees with db.Employees.ensureIndex({"email":"hashed"}) and it works. But when I tried shardCollection again, it still return that error.

What should I do?

Do MongoDB have a rules that if I would add shardKeys on a collection, it (collection) must not exist at first?

Upvotes: 0

Views: 821

Answers (1)

ares
ares

Reputation: 4413

Your index strategy must be same as yout shard strategy. If you have created a hashed index, then you must specify hashed strategy while sharding.

sh.shardCollection("Databases.Employees",{"email":1})

shoule be replace with

sh.shardCollection("Databases.Employees",{"email":"hashed"})

https://docs.mongodb.com/v3.0/tutorial/shard-collection-with-a-hashed-shard-key/#shard-the-collection

Upvotes: 2

Related Questions