What are the sharding algorithms of mongodb?

MongoDB’s sharding algorithm

MongoDB provides two sharding algorithms for distributing data across multiple servers:

1 . Hash sharding

• Description: Use a specific field of the document as the sharding key and hash the document based on the value of the field.
• Advantages: Ensures that data is evenly distributed among shards, thus achieving good load balancing.
• Disadvantages: All documents within the same shard key value range will be stored on the same shard, which may cause hotspot issues.

2. Range sharding

• Description: Use specific fields of the document as the sharding key, and based on that Ranges of fields assign documents to different shards.
• Advantages: Documents with similar value ranges can be stored on the same shard, thereby reducing hotspot issues.
• Disadvantages: Data distribution may be uneven, especially when the shard key value range is discontinuous.

Considerations for choosing an algorithm

Which sharding algorithm to choose depends on the following factors:

• Data Distribution: If the data has a uniform distribution over a certain field, hash sharding is more suitable.
• Load balancing: If you need to ensure load balancing between shards, hash sharding is also preferred.
• Hot Issues: If there are hot issues, range sharding can help store documents with similar values ​​on the same shard.

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