MongoDB Questions and Answers – Sharded Cluster Data Management – 2

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This set of MongoDB online quiz focuses on “Sharded Cluster Data Management – 2”.

1. _______ enables the balancer and waits for balancing to start.
a) sh.waitForBalancer()
b) sh.startBalancer()
c) sh.waitForDLock()
d) all of the mentioned
View Answer

Answer: b
Explanation: sh.waitForDLock() waits for a specified distributed sharded cluster lock.

2. Point out the correct statement.
a) sh.deadForDLock() waits for a specified distributed sharded cluster lock
b) sh.waitForBalancerOff() waits until the balancer stops running
c) sh.statusserver() reports on the status of a sharded cluster, as db.printShardingStatus()
d) all of the mentioned
View Answer

Answer: a
Explanation: sh.stopBalancer() disables the balancer and waits for any in progress balancing rounds to complete.

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3. _________ waits for a change in ping state from one of the mongos in the sharded cluster.
a) sh.waitForBalancer()
b) sh.startBalancer()
c) sh.waitForPingChange()
d) all of the mentioned
View Answer

Answer: c
Explanation: sh.waitForBalancer() waits for the balancer state to change.

4. _______ forces an update to the cluster metadata cached by a mongos.
a) config
b) flushconf
c) flushRouterConfig
d) all of the mentioned
View Answer

Answer: c
Explanation: flushRouterConfig clears the current cluster information cached by a mongos instance and reloads all sharded cluster metadata from the config database.

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5. Point out the wrong statement.
a) moveChunks provides the ability to combine chunks on a single shard
b) setShardVersion is used to set the config server version
c) shardCollection enables the sharding functionality for a collection, allowing the collection to be sharded
d) none of the mentioned
View Answer

Answer: d
Explanation: For a sharded collection, mergeChunks combines contiguous chunk ranges on a shard into a single chunk.

6. Which of the following command that validates index on shard key?
a) checkShardingIndex
b) checkSIndex
c) enableSharding
d) all of the mentioned
View Answer

Answer: a
Explanation: checkShardingIndex is an internal command that supports sharding functionality.

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7. Which of the following command is used to determine split points?
a) splitVector
b) medianKey
c) movePrimary
d) none of the mentioned
View Answer

Answer: a
Explanation: movePrimary reassigns the primary shard when removing a shard from a sharded cluster.

8. You can only issue listShards against the ________ database.
a) local
b) admin
c) temp
d) none of the mentioned
View Answer

Answer: b
Explanation: listShards is only available for mongos instances.

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9. _________ is an internal command that supports the sharding functionality.
a) getBalancerHost()
b) getShardMap
c) enableSharding()
d) all of the mentioned
View Answer

Answer: b
Explanation: sh.getBalancerHost() returns the name of a mongos that’s responsible for the balancer process.

10. ________ command verifies that a process is a mongos.
a) medianKey
b) isdbgrid
c) movePrimary
d) none of the mentioned
View Answer

Answer: b
Explanation: The isdbgrid command is not available to mongod.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter