What is lazy loading in caching, and when should it be used?

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ICSM Computer · Answer

Lazy Loading in Caching (Cache-Aside Pattern)
Lazy Loading, also known as Cache-Aside, is a caching strategy where data is loaded into the cache
only when it is requested. If the requested data is not found in the cache (cache miss), the application fetches it from the database, stores it in the cache, and returns it to the user.
and 
How Lazy Loading Works
Check Cache: The application first checks if the data exists in Redis.Cache Miss: If the data is not found, it fetches it from the database.Cache Update: The fetched data is stored in Redis with an optional expiration time (TTL).Return Data: The data is returned to the user.Subsequent Requests: Future requests will retrieve data from the cache instead of querying the database.
and 
Example in C# using Redis
using StackExchange.Redis;
using System;
public class RedisCacheService
{
    private readonly IDatabase _cache;
    private readonly TimeSpan _cacheExpiry = TimeSpan.FromMinutes(10);
    public RedisCacheService()
    {
        var redis = ConnectionMultiplexer.Connect("localhost");
        _cache = redis.GetDatabase();
    }
    public string GetData(string key)
    {
        string cachedData = _cache.StringGet(key);
        if (!string.IsNullOrEmpty(cachedData))
        {
            Console.WriteLine("Cache Hit");
            return cachedData;
        }
        Console.WriteLine("Cache Miss - Fetching from DB...");
        string dataFromDb = FetchFromDatabase(key); // Simulate DB call
        _cache.StringSet(key, dataFromDb, _cacheExpiry); // Store in cache
        return dataFromDb;
    }
    private string FetchFromDatabase(string key)
    {
        return $"Database Value for {key}"; // Simulated DB fetch
    }
}
// Usage
var cacheService = new RedisCacheService();
string result = cacheService.GetData("user:123");
Console.WriteLine(result);
and 
When to Use Lazy Loading?
Use When:
Data doesn’t change frequently.The cache size should be optimized (only requested data is stored).Stale data is acceptable for a short period.Read-heavy applications where frequent cache hits improve performance.
Avoid When:
Real-time updates are required (use write-through instead).High cache misses would cause initial latency (use preloading or
refresh-ahead strategies).The database cannot handle frequent cache misses efficiently.
and

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What is lazy loading in caching, and when should it be used?

ICSM Computer

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Lazy Loading in Caching (Cache-Aside Pattern)

How Lazy Loading Works

When to Use Lazy Loading?

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