Sharding: How does it work?

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Sharding

Sharding: mongos

• Sharding happens on a collection level
• The sharding key determines how data is distributed

db.runCommand( {
    shardcollection: "demo.cities",
    key: { name: 1 }
} );

• Data is stored in chunks, each with a maximum size of 64MB
• A chunk contains data in the form of a subsection of the shard key
• mongos makes sure that chunks are distributed
• Chunk meta-data is stored in the config servers
• Each shard is a replica-set