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Sharding Reference¶

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Sharding Methods in the `mongo` Shell¶

Name	Description
`sh.getBalancerLockDetails()`	Reports on the balancer lock.
`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.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.enableSharding()`	Enables sharding on a specific database.
`sh.getBalancerHost()`	Deprecated since MongoDB 3.4
`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.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.waitForDLock()`	Internal. Waits for a specified distributed sharded cluster lock.
`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.

Sharding Database Commands¶

The following database commands support sharded clusters.

Name	Description
`addShard`	Adds a shard to a sharded cluster.
`addShardToZone`	Associates a shard with a zone. Supports configuring zones in sharded clusters.
`balancerStart`	Starts a balancer thread.
`balancerStatus`	Returns information on the balancer status.
`balancerStop`	Stops the balancer thread.
`checkShardingIndex`	Internal command that validates index on shard key.
`cleanupOrphaned`	Removes orphaned data with shard key values outside of the ranges of the chunks owned by a shard.
`enableSharding`	Enables sharding on a specific database.
`flushRouterConfig`	Forces an update to the cluster metadata cached by a `mongos`.
`getShardMap`	Internal command that reports on the state of a sharded cluster.
`getShardVersion`	Internal command that returns the config server version.
`isdbgrid`	Verifies that a process is a `mongos`.
`listShards`	Returns a list of configured shards.
`medianKey`	Deprecated internal command. See `splitVector`.
`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.
`setShardVersion`	Internal command to sets the config server version.
`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.
`splitChunk`	Internal command to split chunk. Instead use the methods `sh.splitFind()` and `sh.splitAt()`.
`splitVector`	Internal command that determines split points.
`unsetSharding`	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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