MongoDB sharding algorithm

Mainly two, one is to use the numerical range Division, one is a hash, a bit similar to the memcached cluster mechanism.

The following table compares the pros and cons

sharding Algorithm	Range Query Performance	Data Distribution
Ranged based	Strong, easy to focus on a shard on multiple chunks	Uneven, affects scale out
Hash based	In general, you need to query multiple shard to get results	Uniform

MongoDB also provides a mechanism to customize the algorithm called Tag aware sharding.

The administrator creates some tags that have a range of scopes and puts these tags into each shards.

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MongoDB sharding algorithm