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Articles on Trending Technologies
Technical articles with clear explanations and examples
Difference between Hadoop and MongoDB
Hadoop is a Java-based distributed computing framework designed to store and analyze large volumes of data across multiple computer clusters. It processes enormous amounts of structured and unstructured data through its core components: HDFS (Hadoop Distributed File System) for storage and MapReduce for parallel data processing. MongoDB is an open-source NoSQL document database that stores data in BSON format rather than traditional tables, rows, and columns. It's designed to solve performance, availability, and scalability issues of SQL-based databases by offering a flexible, document-oriented approach to data storage. What is Hadoop? Apache Hadoop is a distributed computing platform ...
Read MoreSignUp form using Node and MongoDB
In this article, we will create a simple user sign-up form using Node.js and MongoDB. When users fill out the form and click submit, their details will be saved to the MongoDB database. Installation Before creating the sign-up form, install the following dependencies: Express - Web framework for Node.js to handle HTTP requests npm install express --save Body-parser - Middleware to parse HTTP POST data npm install body-parser --save Mongoose - MongoDB ...
Read MoreConnecting MongoDB with NodeJS
To connect MongoDB with Node.js, use the MongoClient.connect() method from the mongodb package. This asynchronous method establishes a connection between your Node.js application and the MongoDB server. Syntax MongoClient.connect(url, options, callback) Parameters: url − Connection string specifying the MongoDB server location and port options − Optional configuration object (e.g., useUnifiedTopology: true) callback − Function executed after connection attempt with error and client parameters Installation and Setup First, install the MongoDB driver for Node.js ? npm install mongodb --save Start your MongoDB server ? mongod --dbpath=data ...
Read MoreQuerying on an array of objects for specific nested documents with MongoDB?
To query on an array of objects for nested documents in MongoDB, use the find() method with the $elemMatch operator in projection to return only matching array elements. Syntax db.collection.find( {}, { arrayField: { $elemMatch: { condition } } } ); Sample Data db.demo763.insertOne({ _id: 1, ...
Read MoreMongoDB aggregation and projection?
MongoDB aggregation with projection allows you to transform and reshape documents by selecting specific fields, computing new values, and controlling the output structure. The $project stage in the aggregation pipeline passes documents with requested fields to the next stage. Syntax db.collection.aggregate([ { $project: { field1: 1, // Include field field2: 0, // Exclude field ...
Read MoreCheck for duplicates in an array in MongoDB?
To check for duplicates in an array in MongoDB, use the $unwind and $group operators within an aggregation pipeline to identify array elements that appear more than once in the same document. Syntax db.collection.aggregate([ { $project: { arrayField: 1 } }, { $unwind: "$arrayField" }, { $group: { _id: { _id: "$_id", value: "$arrayField" }, count: { $sum: 1 } } }, { $match: { count: { $gt: 1 } } }, { $group: { _id: "$_id._id", ...
Read MoreSort MongoDB field which contains both integer and decimal values?
To sort a MongoDB field containing both integer and decimal values, use the sort() method. MongoDB automatically handles mixed numeric types (integers and decimals) in the same field and sorts them by their numeric value. Syntax db.collection.find().sort({fieldName: 1}); // 1 for ascending, -1 for descending Sample Data db.demo755.insertMany([ {"Value": 10}, {"Value": 10.5}, {"Value": 9.5}, {"Value": 12.5}, {"Value": 11.5}, {"Value": 6} ]); { ...
Read MoreHow to convert birth date records to age with MongoDB
To convert birth date records to age in MongoDB, use the $dateDiff operator or calculate the difference between the current date and birth date using $subtract and $divide operators in an aggregation pipeline. Syntax db.collection.aggregate([ { $project: { age: { $divide: [ ...
Read MoreFilter specific values from a MongoDB document
To filter specific values from a MongoDB document, use the $filter operator in aggregation pipelines. This operator allows you to select array elements that match specific conditions and return only those elements. Syntax { $filter: { input: "$arrayField", as: "variable", cond: { condition } } } Sample Data db.demo751.insertOne({ _id: 101, details: [ ...
Read MoreHow to get max values for distinct elements in MongoDB
To get max values for distinct elements in MongoDB, use the $group operator with $max to find the highest value for each distinct element. This aggregation pipeline groups documents by a field and returns the maximum value within each group. Syntax db.collection.aggregate([ { $group: { _id: "$fieldName", maxValue: { $max: "$valueField" } } ...
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