What should I do after Sharding a collection in MongoDB?

What should I do after Sharding a collection in MongoDB?

If you must change a shard key after sharding a collection, the best option is to: dump all data from MongoDB into an external format. drop the original sharded collection. configure sharding using a more ideal shard key. pre-split the shard key range to ensure initial even distribution. restore the dumped data into MongoDB.

What should I do if I need to change my shard key in MongoDB?

In MongoDB 4.2 and earlier, if you must change a shard key after sharding a collection and cannot upgrade, the best option is to: dump all data from MongoDB into an external format. drop the original sharded collection. configure sharding using a more ideal shard key. pre-split the shard key range to ensure initial even distribution.

Is there a way to unshard a MongoDB cluster?

Sharded cluster infrastructure requirements and complexity require careful planning, execution, and maintenance. Once a collection has been sharded, MongoDB provides no method to unshard a sharded collection. Careful consideration in choosing the shard key is necessary for ensuring cluster performance and efficiency.

When to create a supporting Index in MongoDB?

When sharding an empty collection, MongoDB creates the supporting index if the collection does not already have an appropriate index for the specified shard key. See Shard Key Indexes.

When to use hashed shard key in MongoDB?

“hashed” to specify a hashed shard key. shard key must be supported by an index. Unless the collection is empty, the index must exist prior to the shardCollection command. If the collection is empty, MongoDB creates the index prior to sharding the collection if the index that can support the shard key does not already exist.

What are the components of a MongoDB sharded cluster?

The trade off is increased complexity in infrastructure and maintenance for the deployment. MongoDB supports horizontal scaling through sharding. A MongoDB sharded cluster consists of the following components: shard: Each shard contains a subset of the sharded data. Each shard can be deployed as a replica set.

How many chunk migrations can MongoDB do at a time?

Changed in version 3.4: Starting in MongoDB 3.4, MongoDB can perform parallel chunk migrations. Observing the restriction that a shard can participate in at most one migration at a time, for a sharded cluster with n shards, MongoDB can perform at most n/2 (rounded down) simultaneous chunk migrations.

How does shard migration work in MongoDB balancer?

To migrate multiple chunks from a shard, the balancer migrates the chunks one at a time. However, the balancer does not wait for the current migration’s delete phase to complete before starting the next chunk migration. See Chunk Migration for the chunk migration process and the delete phase.

How to connect to a sharded MongoDB cluster?

You can now connect to the sharded cluster using the mongo shell. Connect a mongo shell to the mongos . Specify the host and port on which the mongos is running: Once you have connected the mongo shell to the mongos, continue to the next procedure to add shards to the cluster.

What happens when MongoDB pool is no longer in use?

These pools do not shrink when the number of clients decreases. This can lead to an unused mongos with a large number of open connections. If the mongos is no longer in use, it is safe to restart the process to close existing connections. See the System Resource Utilization section of the UNIX ulimit Settings document.