Sharding Reference

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Sharding Methods in mongosh

Sharding Database Commands
Reference Documentation

MongoDB 5.0 is end of life as of October 2024. This version of the documentation is no longer supported. To upgrade your 5.0 deployment, see the MongoDB 6.0 upgrade procedures.

Sharding Methods in `mongosh`

Name	Description
`sh.abortReshardCollection()`	Aborts a resharding operation. New in version 5.0.
`sh.addShard()`	Adds a shard to a sharded cluster.
`sh.addShardTag()`	In MongoDB 3.4, this method aliases to `sh.addShardToZone()`.
`sh.addShardToZone()`	Associates a shard to a zone. Supports configuring zones in sharded clusters.
`sh.addTagRange()`	In MongoDB 3.4, this method aliases to `sh.updateZoneKeyRange()`.
`sh.balancerCollectionStatus()`	Returns information on whether the chunks of a sharded collection are balanced.
`sh.commitReshardCollection()`	Forces a resharding operation to block writes and complete. New in version 5.0.
`sh.disableBalancing()`	Disable balancing on a single collection in a sharded database. Does not affect balancing of other collections in a sharded cluster.
`sh.enableBalancing()`	Activates the sharded collection balancer process if previously disabled using `sh.disableBalancing()`.
`sh.disableAutoSplit()`	Disables auto-splitting for the sharded cluster.
`sh.enableAutoSplit()`	Enables auto-splitting for the sharded cluster.
`sh.enableSharding()`	Enables sharding on a specific database.
`sh.getBalancerState()`	Returns a boolean to report if the balancer is currently enabled.
`sh.removeTagRange()`	In MongoDB 3.4, this method aliases to `sh.removeRangeFromZone()`.
`sh.removeRangeFromZone()`	Removes an association between a range of shard keys and a zone. Supports configuring zones in sharded clusters.
`sh.help()`	Returns help text for the `sh` methods.
`sh.isBalancerRunning()`	Returns a boolean to report if the balancer process is currently migrating chunks.
`sh.moveChunk()`	Migrates a chunk in a sharded cluster.
`sh.removeShardTag()`	In MongoDB 3.4, this method aliases to `sh.removeShardFromZone()`.
`sh.removeShardFromZone()`	Removes the association between a shard and a zone. Use to manage zone sharding.
`sh.reshardCollection()`	Initiates a resharding operation to change the shard key for a collection, changing the distribution of your data. New in version 5.0.
`sh.setBalancerState()`	Enables or disables the balancer which migrates chunks between shards.
`sh.shardCollection()`	Enables sharding for a collection.
`sh.splitAt()`	Divides an existing chunk into two chunks using a specific value of the shard key as the dividing point.
`sh.splitFind()`	Divides an existing chunk that contains a document matching a query into two approximately equal chunks.
`sh.startBalancer()`	Enables the balancer and waits for balancing to start.
`sh.status()`	Reports on the status of a sharded cluster, as `db.printShardingStatus()`.
`sh.stopBalancer()`	Disables the balancer and waits for any in progress balancing rounds to complete.
`sh.waitForBalancer()`	Internal. Waits for the balancer state to change.
`sh.waitForBalancerOff()`	Internal. Waits until the balancer stops running.
`sh.waitForPingChange()`	Internal. Waits for a change in ping state from one of the `mongos` in the sharded cluster.
`sh.updateZoneKeyRange()`	Associates a range of shard keys to a zone. Supports configuring zones in sharded clusters.
`convertShardKeyToHashed()`	Returns the hashed value for the input.

Sharding Database Commands

The following database commands support sharded clusters.

Name	Description
`abortReshardCollection`	Aborts a resharding operation. New in version 5.0.
`addShard`	Adds a shard to a sharded cluster.
`addShardToZone`	Associates a shard with a zone. Supports configuring zones in sharded clusters.
`balancerCollectionStatus`	Returns information on whether the chunks of a sharded collection are balanced.
`balancerStart`	Starts a balancer thread.
`balancerStatus`	Returns information on the balancer status.
`balancerStop`	Stops the balancer thread.
`clearJumboFlag`	Clears the `jumbo` flag for a chunk.
`cleanupOrphaned`	Removes orphaned data with shard key values outside of the ranges of the chunks owned by a shard.
`cleanupReshardCollection`	Cleans up a failed resharding operation. New in version 5.0.
`commitReshardCollection`	Forces a resharding operation to block writes and complete. New in version 5.0.
`enableSharding`	Enables sharding on a specific database.
`flushRouterConfig`	Forces a `mongod` / `mongos` instance to update its cached routing metadata.
`getShardMap`	Internal command that reports on the state of a sharded cluster.
`isdbgrid`	Verifies that a process is a `mongos`.
`listShards`	Returns a list of configured shards.
`moveChunk`	Internal command that migrates chunks between shards.
`movePrimary`	Reassigns the primary shard when removing a shard from a sharded cluster.
`mergeChunks`	Provides the ability to combine chunks on a single shard.
`removeShard`	Starts the process of removing a shard from a sharded cluster.
`removeShardFromZone`	Removes the association between a shard and a zone. Supports configuring zones in sharded clusters.
`reshardCollection`	Initiates a resharding operation to change the shard key for a collection, changing the distribution of your data. New in version 5.0.
`shardCollection`	Enables the sharding functionality for a collection, allowing the collection to be sharded.
`shardingState`	Reports whether the `mongod` is a member of a sharded cluster.
`split`	Creates a new chunk.
`unsetSharding`	Removed in MongoDB 5.0. Internal command that affects connections between instances in a MongoDB deployment.
`updateZoneKeyRange`	Adds or removes the association between a range of sharded data and a zone. Supports configuring zones in sharded clusters.

Reference Documentation

Operational Restrictions: Requirement for deploying a sharded cluster
Troubleshoot Sharded Clusters: Common strategies for troubleshooting sharded cluster deployments.
Config Database: Complete documentation of the content of the local database that MongoDB uses to store sharded cluster metadata.

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Drop Hashed Shard Key Index

Operational Restrictions