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Advantages & Downsides of MongoDB

✅ Advantages​

1. Flexibility​

  • Fields can differ between documents, making MongoDB perfect for event-based systems.
  • Supports dynamic structures, allowing future updates with minimal disruptions.

2. Ease of Use​

  • Multi-Language Support: Works with JavaScript, Java, C#, C++, Python, and more.
  • Data Retrieval Simplicity: Simple queries reduce complexity depending on the chosen language.
JavaScript
const database = 'Nameless_DB';
const collection = 'mainEventCollection';

use(database);

db.mainEventCollection.find();
Java (Spring Boot)
private MainEventEntityRepository mainEventEntityRepository;

public List<MainEvent> GetAllEvents(){
    return mainEventEntityRepository.findAll();
}

🚫 Downsides​

1. Data Duplication Risk​

  • Due to its document-based structure, duplicate data can occur.
  • Solution: Normalize data or use relationships where possible.

2. Learning Curve​

  • SQL Incompatibility: MongoDB isn’t SQL-based, meaning:
    • SQL Knowledge Does Not Transfer Easily.
    • Requires learning new querying methods.

3. Aggregation Queries Complexity​

  • Aggregated data querying may differ between languages.
  • Syntax Variations: Queries in JavaScript may be different from those in Java or Python.
Query in JavaScript
const database = 'Nameless DB';
const collection = 'mainEventCollection';

use(database);

db[collection].aggregate([
  {
    $unwind: {
      path: "$eventPayload.event.data.items",
      preserveNullAndEmptyArrays: true
    }
  },
  {
    $group: {
      _id: "$eventPayload.event.data.items.items_name",
      count: { $sum: 1 }
    }
  },
  {
    $match: {
      _id: { $ne: null }
    }
  },
  {
    $project: {
      item_name: "$_id",
      count: 1,
      _id: 0
    }
  }
]);
Query in Java
public List<ItemCount> getItemCountTrucks() {
        Aggregation aggregation = Aggregation.newAggregation(
                Aggregation.unwind("eventPayload.event.data.items", true),
                Aggregation.group("eventPayload.event.data.items.item_name")
                        .count().as("count"),
                Aggregation.match(Criteria.where("_id").ne(null)),
                Aggregation.project("count")
                        .and("_id").as("item")
                        .andExclude("_id")
        );

        AggregationResults<ItemCountEntity> results = mongoTemplate.aggregate(aggregation, MainEventEntity.class, ItemCountEntity.class);
        return convertItemNameToDomainList(results.getMappedResults());
    }