Below are Some Important MongoDB
Question 1: What is MongoDB, and why is it different from traditional relational databases? Answer: MongoDB is a NoSQL document-oriented database. It's different from relational databases as it uses a flexible, schema-less data model and JSON-like documents. Question 2: How do you start a MongoDB server? Answer: To start a MongoDB server, use the mongod command. For example: bashCopy code mongod --dbpath /path/to/data/directory Question 3: Explain the concept of a collection and a document in MongoDB. Answer: A collection is a group of MongoDB documents, while a document is a set of key-value pairs in a JSON-like format. Question 4: What is the primary key in MongoDB, and how is it generated? Answer: The primary key in MongoDB is the _id field. It's generated automatically when a new document is inserted if not provided explicitly. Question 5: How can you create a new database in MongoDB? Answer: Databases in MongoDB are created implicitly when you insert data into a new database name. Question 6: Explain the difference between a replica set and a sharded cluster in MongoDB. Answer: A replica set is a group of MongoDB servers that store the same data for redundancy. A sharded cluster is a group of servers that divide data into shards for better scalability. Question 7: What is the purpose of the mongodump and mongorestore utilities in MongoDB? Answer: mongodump is used for creating backups of MongoDB databases, and mongorestore is used to restore them. Question 8: How can you create an index in MongoDB? Answer: You can create an index using the createIndex() method. For example: javascriptCopy code db.collection.createIndex({ field: 1 }) Question 9: Explain the concept of aggregation in MongoDB. Answer: Aggregation in MongoDB involves processing and transforming data to get insights or summaries. It's achieved using the $group, $match, $project, and other pipeline stages. Question 10: How do you monitor MongoDB server status? Answer: You can use commands like db.serverStatus(), mongostat, and mongotop to monitor the MongoDB server's status and performance. Question 11: What is a TTL index in MongoDB, and how is it used? Answer: A TTL (Time-to-Live) index automatically removes documents from a collection after a certain period of time. It's used to manage data expiration. Question 12: How can you perform a rolling restart of a MongoDB replica set? Answer: You can restart the nodes in a replica set one by one, allowing the primary to step down temporarily, while the other nodes continue to serve traffic. Question 13: Explain the concept of database profiling in MongoDB. Answer: Profiling in MongoDB involves tracking query performance to identify slow or resource-intensive queries. Question 14: What is the purpose of the mongostat utility in MongoDB? Answer: mongostat provides a live view of the MongoDB server's status, including various performance metrics. Question 15: How do you enable authentication in MongoDB? Answer: To enable authentication, you need to configure a MongoDB user and password in the mongod configuration file. Question 16: Explain the concept of horizontal scaling in MongoDB using sharding. Answer: Sharding involves distributing data across multiple servers to improve performance and handle large datasets. Question 17: How can you configure MongoDB to use SSL encryption for connections? Answer: You can configure MongoDB to use SSL by providing the appropriate SSL certificate and key files in the mongod configuration. Question 18: What is the purpose of the mongo shell in MongoDB? Answer: The mongo shell is a command-line interface for interacting with the MongoDB server, querying data, and performing administrative tasks. Question 19: Explain the use of the explain() method in MongoDB. Answer: The explain() method is used to view the execution plan of a query, helping to optimize query performance. Question 20: How can you monitor and manage MongoDB locks? Answer: MongoDB uses a per-database locking mechanism. You can use commands like db.currentOp() to monitor and troubleshoot locks. Question 21: What is the purpose of the mongos process in MongoDB sharding? Answer: The mongos process is a query router that directs client requests to the appropriate shard in a sharded cluster. Question 22: Explain the concept of read and write concerns in MongoDB. Answer: Read and write concerns define how the data consistency and availability are guaranteed for read and write operations in MongoDB. Question 23: How can you perform a backup and restore of a sharded cluster in MongoDB? Answer: Use the mongodump utility to create backups and the mongorestore utility to restore data for each shard and the config servers. Question 24: Describe the purpose of the journal in MongoDB. Answer: The journal is a feature in MongoDB that helps in crash recovery by recording write operations in a journal file. Question 25: How can you enable profiling and view profile data in MongoDB? Answer: You can enable profiling using the profile option in the configuration file or by using the profile command. Profile data can be viewed using the system.profile collection. Question 26: Explain the concept of zones in MongoDB sharding. Answer: Zones are used in MongoDB sharding to control how data is distributed across shards based on a specific range or criteria. Question 27: How do you enable the authentication mechanism in MongoDB? Answer: To enable authentication, set the security.authorization parameter to enabled in the MongoDB configuration file. Question 28: Explain the purpose of the mongorestore utility in MongoDB sharding. Answer: mongorestore is used to restore data to a sharded cluster, preserving the distribution across shards. Question 29: What is the role of the mongod configuration file in MongoDB? Answer: The mongod configuration file is used to specify various settings and options for the MongoDB server. Question 30: How can you manage users and roles in MongoDB? Answer: You can use commands like db.createUser() and db.updateUser() to manage users and roles in MongoDB. Question 31: Explain the concept of WiredTiger storage engine in MongoDB. Answer: WiredTiger is the default storage engine in MongoDB, known for its support for document-level concurrency control and compression. Question 32: How can you monitor and manage MongoDB memory usage? Answer: You can use commands like db.stats() and db.serverStatus() to monitor memory usage, and adjust cache settings for optimization. Question 33: Describe the purpose of the mongostore utility in MongoDB sharded clusters. Answer: mongostore is used to migrate data from a standalone instance to a sharded cluster, ensuring even distribution across shards. Question 34: Explain the concept of a database profiler in MongoDB. Answer: The database profiler in MongoDB collects information about database operations, queries, and performance. Question 35: How can you monitor and manage MongoDB disk space usage? Answer: You can use the db.stats() command and system monitoring tools to monitor disk space usage and manage storage. Question 36: Describe the purpose of the oplog in MongoDB replication. Answer: The oplog (operation log) is a capped collection that records all changes to the data in a replica set. It's used for replication and recovery. Question 37: Explain the use of the replSetGetStatus command in MongoDB. Answer: The replSetGetStatus command provides detailed information about the status and configuration of a replica set. Question 38: How can you monitor and manage MongoDB journaling? Answer: MongoDB journaling can be monitored using the db.serverStatus() command. To manage it, you can set the storage.journal.enabled parameter in the configuration. Question 39: Describe the purpose of the failover mechanism in MongoDB replica sets. Answer: Failover is the process where a secondary node becomes the primary node if the current primary node becomes unavailable. Question 40: Explain the use of the mongotop utility in MongoDB. Answer: The mongotop utility provides real-time statistics about MongoDB operations, helping you identify which operations are consuming the most time. Question 41: How can you monitor and manage MongoDB security using auditing? Answer: MongoDB auditing can be enabled to track and log various operations for security analysis. It can be managed using configuration options. Question 42: Describe the purpose of the mongofiles utility in MongoDB. Answer: The mongofiles utility is used to work with files stored in the MongoDB GridFS system. Question 43: Explain the use of the getLastError command in MongoDB. Answer: The getLastError command returns the status of the most recent write operation, helping to ensure data consistency. Question 44: How can you monitor and manage MongoDB query performance? Answer: You can use the db.currentOp() command, the explain() method, and query profiling to monitor and improve query performance. Question 45: Describe the purpose of the arbiter in MongoDB replica sets. Answer: An arbiter is a lightweight member of a replica set that helps in achieving consensus in the election of a primary node. Question 46: Explain the use of the replSetInitiate command in MongoDB. Answer: The replSetInitiate command is used to initialize a new replica set by configuring its members and electing a primary. Question 47: How can you monitor and manage MongoDB network activity? Answer: You can use tools like netstat, mongostat, and MongoDB logs to monitor network activity and diagnose issues. Question 48: Describe the purpose of the balancer in MongoDB sharding. Answer: The balancer in MongoDB sharding is responsible for redistributing chunks of data across shards to maintain an even distribution. Question 49: Explain the use of the db.runCommand() method in MongoDB. Answer: The db.runCommand() method is used to run administrative and diagnostic commands in MongoDB. Question 50: How can you monitor and manage MongoDB backup and recovery strategies? Answer: You can use tools like mongodump, mongorestore, and database snapshots to implement and manage backup and recovery strategies.
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