Shard a Collection
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To shard a collection, you must specify the full namespace of the
collection that you want to shard and the shard key. You can use the
shard a collection:
sh.shardCollection(<namespace>, <key>) // Optional parameters omitted
Specify the full namespace of the collection that you want to shard (
Specify a document
For more information on the sharding method, see
Shard Key Fields and Values
Missing Shard Key Fields
Starting in version 4.4, documents in sharded collections can be
missing the shard key fields. A missing shard key falls into the
same range as a
null-valued shard key. See Missing Shard Key Fields.
In version 4.2 and earlier, shard key fields must exist in every document to be able to shard a sharded collection. To set missing shard key fields, see Set Missing Shard Key Fields.
Change a Document's Shard Key Value
Starting in MongoDB 4.2, you can update a document's shard key value
unless the shard key field is the immutable
_id field. In
MongoDB 4.2 and earlier, a document's shard key field value is
For details on updating the shard key value, see Change a Document's Shard Key Value.
Change a Collection's Shard Key
Starting in MongoDB 5.0, you can reshard a collection by changing a document's shard key.
Starting in MongoDB 4.4, you can refine a shard key by adding a suffix field or fields to the existing shard key.
In MongoDB 4.2 and earlier, the choice of shard key cannot be changed after sharding.