is there a persistent storage option for sqlite so
that the data gets persisted between restarts
Yes, SQLite provides several options for persistent storage, ensuring that data is retained
between restarts. Here are some methods to achieve persistent storage with SQLite:
1. On-Disk Databases
SQLite databases are typically stored on disk by default. To persist data, you simply need to
create or connect to a database file instead of using the :memory: option. For example, in
Node.js, you can create a persistent database by specifying a file name:
const db = new Database("db.sqlite");
This approach ensures that data is saved to the file and can be retrieved after a restart [1] .
2. Attaching an On-Disk Database to an In-Memory Database
If you are using an in-memory database (:memory:) and want to persist some data, you can
attach an on-disk database and transfer data between them using SQL queries. Here's how you
can attach a database:
ATTACH "atest.db" as a;
Then, use SQL to copy data from the in-memory tables to the on-disk tables [2] .
3. Dumping and Loading
Another method is to dump the in-memory database to a file and load it back when needed. You
can use the .dump command in SQLite to export the database schema and data to a SQL file,
which can then be loaded into a new database:
.once 'path/to/dump.sql'
.dump
Later, you can open or create an on-disk database and run the dump script to populate it [2] .
4. Volumes in Docker
If you are using Docker, you can persist SQLite data by mounting a volume to the container's
directory where the database file is stored. This ensures that data is persisted across container
restarts [3] .
5. VFS and Relaxed Durability
SQLite also supports various Virtual File System (VFS) implementations for custom storage
solutions. Additionally, you can configure durability settings using PRAGMA synchronous to balance
performance and data safety [4] . However, these are more advanced configurations and may
not be necessary for simple persistence needs.
In summary, the most straightforward way to ensure persistence with SQLite is to use an on-disk
database by specifying a file name when creating or connecting to the database.
⁂
SQLite Support in .NET 8.0
SQLite is supported in .NET 8.0 through the Microsoft.EntityFrameworkCore.Sqlite package,
which is a part of Entity Framework Core. You can install this package using NuGet to use SQLite
databases in your .NET applications [5] . Additionally, the System.Data.SQLite package provides
direct access to SQLite databases in .NET, similar to how it is used in earlier versions [6] .
SQLite Support on iPadOS 18 and Above
On iPadOS, SQLite can be used for local data storage in apps. You can manage SQLite
databases using libraries like FMDB, which is a popular choice for iOS and iPadOS
development [7] . For storing the database, you should use the Documents directory if the data is
user-generated or critical for app functionality. This ensures that the data is backed up and
accessible via file sharing [8] .
Summary
.NET 8.0: SQLite is supported via Microsoft.EntityFrameworkCore.Sqlite.
iPadOS 18 and Above: SQLite is supported using libraries like FMDB, with data stored in the
Documents directory for user-generated content.
Both platforms support SQLite for persistent storage, making it a viable choice for cross-
platform development.
⁂
SQLite Support on iPadOS 18 and Above with .NET 8.0
When developing apps for iPadOS using .NET 8.0, SQLite can be used for local data storage.
However, there are some considerations:
1. .NET MAUI and SQLite:
.NET MAUI is the framework used for cross-platform app development, including iOS
and iPadOS.
SQLite can be integrated into .NET MAUI apps using libraries like
Microsoft.Data.Sqlite or sqlite-net.
2. Compatibility Issues:
There have been reports of issues with certain SQLite packages in .NET MAUI apps,
especially when targeting iOS simulators or devices. For example, sqlite-net-sqlcipher
has been reported to cause linker errors when building for iOS simulators with .NET
8.0 [9] [10] .
Ensure that the SQLite package you choose is compatible with .NET 8.0 and iOS
platforms.
3. iPadOS 18 Support:
iPadOS 18 is supported by .NET MAUI, allowing you to develop and deploy apps on this
platform [11] .
However, specific SQLite library compatibility might require additional configuration or
troubleshooting.
4. Recommendations:
Use Microsoft.Data.Sqlite or similar libraries that are known to work with .NET 8.0 and
iOS platforms.
Test your app thoroughly on iPadOS 18 to ensure that SQLite functionality works as
expected.
In summary, while SQLite can be used on iPadOS 18 with .NET 8.0, you should carefully select
compatible libraries and test your app to avoid potential issues.
⁂
suggest me one azure service that I can use for
feature toggles in my application. I need feature
toggle at country and / or user level.
For implementing feature toggles at the country and/or user level in your application, Azure App
Configuration is a suitable Azure service. It provides robust support for feature flags, including
targeting filters that allow you to dynamically enable or disable features for specific users or
groups.
Key Features of Azure App Configuration for Feature Toggles:
1. Targeting Filters:
Azure App Configuration allows you to define targeting filters that can enable or disable
features based on user attributes, such as country or user ID. This is particularly useful
for implementing feature toggles at the country or user level.
2. Variant Feature Flags:
You can create variant feature flags, which allow multiple variations of a feature flag.
This is useful for A/B testing or rolling out features to specific groups.
3. Integration with .NET:
Azure App Configuration integrates well with .NET applications. You can use the
Microsoft.FeatureManagement NuGet package to manage feature flags in your .NET
apps.
4. Centralized Management:
Feature flags are managed centrally through the Azure portal, making it easy to control
feature availability across different environments and user segments.
5. CI/CD Integration:
Azure App Configuration integrates with Azure DevOps, allowing you to automate
feature flag management as part of your CI/CD pipeline.
Example of Using Azure App Configuration for Feature Toggles
To implement feature toggles at the country level, you can follow these steps:
1. Create a Feature Flag:
Use the Azure portal to create a feature flag in Azure App Configuration.
Define a targeting filter based on country.
2. Integrate with Your Application:
Install the necessary NuGet packages (Microsoft.FeatureManagement and
Microsoft.Extensions.Configuration.AzureAppConfiguration) in your .NET project.
Configure your application to read feature flags from Azure App Configuration.
3. Implement Feature Toggle Logic:
Use the feature flag in your application logic to enable or disable features based on the
country.
Here's a simplified example of how you might use a feature flag in a .NET application:
using Microsoft.FeatureManagement;
public class MyService
{
private readonly IFeatureManagerSnapshot _featureManager;
public MyService(IFeatureManagerSnapshot featureManager)
{
_featureManager = featureManager;
}
public async Task DoSomethingAsync(string countryCode)
{
if (await _featureManager.IsEnabledAsync("MyFeatureFlag", new FeatureFilterEvalua
{
// Feature is enabled for this country, perform action
}
else
{
// Feature is disabled for this country
}
}
}
This approach allows you to dynamically control feature availability based on user attributes like
country, making Azure App Configuration a powerful tool for feature toggle management.
⁂
My application will have internet access only
sometimes. So I need a way to first get my feature
toggles from Azure App Configuration and store
locally. Update them whenever internet is
available. The local storage should be corruption
free / crash free. All programming is done in .NET
8.0 and on iPadOS 18 and above.
For implementing offline-capable feature toggles with Azure App Configuration in a .NET 8.0
app on iPadOS 18+, here's a robust solution that combines Azure services with local caching
and crash resilience:
Solution Architecture
1. Azure App Configuration
Centralized feature toggle management with dynamic updates and user/country targeting.
2. SQLite Local Cache
Persistent offline storage for feature flags (ACID-compliant and corruption-resistant).
3. Synchronization Service
Background sync when internet is available.
Implementation Steps
1. Configure Azure App Configuration with Caching
var builder = WebApplication.CreateBuilder(args);
// Enable caching with 5-minute refresh interval
builder.Configuration.AddAzureAppConfiguration(options =>
{
options.Connect("<AZURE_CONNECTION_STRING>")
.UseFeatureFlags(flags =>
{
flags.CacheExpirationInterval = TimeSpan.FromMinutes(5);
})
.ConfigureRefresh(refresh =>
{
refresh.Register("FeatureFlags:Sentinel", refreshAll: true)
.SetCacheExpiration(TimeSpan.FromDays(1));
});
});
builder.Services.AddFeatureManagement();
2. Implement SQLite Local Storage
// Install packages:
// dotnet add package Microsoft.EntityFrameworkCore.Sqlite
// dotnet add package Microsoft.FeatureManagement
public class FeatureFlagCacheContext : DbContext
{
public DbSet<FeatureFlag> FeatureFlags { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder options)
=> options.UseSqlite("Data Source=featureflags.db");
}
public class LocalFeatureManager : IFeatureManager
{
private readonly FeatureFlagCacheContext _db;
private readonly IFeatureManager _azureFeatureManager;
public LocalFeatureManager(FeatureFlagCacheContext db, IFeatureManager azureFeatureMa
{
_db = db;
_azureFeatureManager = azureFeatureManager;
}
public async Task<bool> IsEnabledAsync(string feature)
{
if (Connectivity.NetworkAccess == NetworkAccess.Internet)
{
var azureValue = await _azureFeatureManager.IsEnabledAsync(feature);
await UpdateLocalCache(feature, azureValue);
return azureValue;
}
else
{
return await _db.FeatureFlags
.Where(f => f.Name == feature)
.Select(f => f.IsEnabled)
.FirstOrDefaultAsync();
}
}
}
3. Crash-Resistant Sync Mechanism
public class FeatureFlagSyncService
{
private readonly FeatureFlagCacheContext _db;
private readonly IFeatureManager _featureManager;
public async Task SyncFeatureFlags()
{
try
{
await using var transaction = await _db.Database.BeginTransactionAsync();
var flags = await _featureManager.GetFeatureNamesAsync();
foreach (var flag in flags)
{
var isEnabled = await _featureManager.IsEnabledAsync(flag);
var entity = await _db.FeatureFlags.FindAsync(flag);
if (entity == null)
{
_db.FeatureFlags.Add(new FeatureFlag
{
Name = flag,
IsEnabled = isEnabled,
LastSynced = DateTime.UtcNow
});
}
else
{
entity.IsEnabled = isEnabled;
entity.LastSynced = DateTime.UtcNow;
}
}
await _db.SaveChangesAsync();
await transaction.CommitAsync();
}
catch (Exception ex)
{
// Implement retry logic with exponential backoff
}
}
}
Key Components
Azure Integration
Use Microsoft.Azure.AppConfiguration.AspNetCore for config management [12] [13]
Leverage built-in caching with CacheExpirationInterval [12]
Local Storage
SQLite ensures ACID compliance for crash safety [Previous SQLite answers]
Entity Framework Core for data access [13]
Synchronization
Check connectivity with Microsoft.Maui.Essentials
Transactional updates prevent partial writes [14] [15]
Error Handling
Retry policies for transient failures
Fallback to last-known values when offline
Usage Pattern
// In your feature-dependent code:
var featureManager = services.GetRequiredService<LocalFeatureManager>();
if (await featureManager.IsEnabledAsync("NewSearchExperience"))
{
// Enable feature
}
This solution provides:
✅ Offline-first functionality with SQLite persistence
✅ Automatic synchronization when connectivity resumes
✅ Crash resistance through transactional updates
✅ Platform compliance with iPadOS 18 background restrictions [14]
For country/user-level targeting, extend the FeatureFlag entity to include user/region metadata
and modify the query logic accordingly [12] [16] .
⁂
for feature flags, my requirement is as follows:
take 1. all feature flags that are enabled for the
country but not disabled at user level AND 2. take
all feature flags that are enabled at user level
irrespective of their state at country level. Does
Azure App Configuration support this? How to
achieve this with Azure app configuration
Azure App Configuration supports your requirement through custom feature filter chaining and
targeting filter configuration, but requires careful implementation. Here's how to achieve this:
1. Feature Flag Configuration Strategy
Use two separate targeting filters with priority ordering:
"FeatureX": {
"EnabledFor": [
{
"Name": "Microsoft.Targeting",
"Parameters": {
"Audience": {
"Users": ["user1", "user2"], // User-level override
"DefaultRolloutPercentage": 0
}
}
},
{
"Name": "Microsoft.Targeting",
"Parameters": {
"Audience": {
"Groups": [{"Name": "CountryA", "RolloutPercentage": 100}],
"DefaultRolloutPercentage": 0,
"Exclusion": {"Users": ["user3"]} // Country-level disable
}
}
}
]
}
2. Custom Evaluation Logic
Implement a custom FeatureFilter to combine rules:
[FilterAlias("CountryUserPriorityFilter")]
public class CountryUserPriorityFilter : IFeatureFilter
{
public Task<bool> EvaluateAsync(FeatureFilterEvaluationContext context)
{
var settings = context.Parameters.Get<CountryUserSettings>();
var user = GetCurrentUser();
var country = GetUserCountry();
// Rule 1: User-level override (enabled)
if (settings.UserOverrides.Contains(user.Id))
return Task.FromResult(true);
// Rule 2: Country enabled AND not user-disabled
return Task.FromResult(
settings.CountryEnabled.Contains(country) &&
!settings.UserExclusions.Contains(user.Id)
);
}
}
3. Configuration Setup in Azure Portal
1. Create composite feature flag with two filters:
First priority: User-level targeting
Second priority: Country-level targeting
2. Custom parameters schema:
{
"CountryEnabled": ["US", "CA"],
"UserOverrides": ["admin1", "premium_user42"],
"UserExclusions": ["legacy_user7"]
}
4. Implementation in .NET
services.AddFeatureManagement()
.AddFeatureFilter<CountryUserPriorityFilter>();
// Usage
var context = new FeatureFilterEvaluationContext {
Parameters = new ConfigurationSettings {
["CountryEnabled"] = "US,CA",
["UserOverrides"] = "admin1,premium_user42",
["UserExclusions"] = "legacy_user7"
}
};
bool isEnabled = await featureManager.IsEnabledAsync("FeatureX", context);
Key Implementation Notes:
1. Evaluation Order
Azure evaluates filters top-to-bottom. User-level rules must be listed first [17] [18] .
2. Data Freshness
Use FeatureManagerSnapshot for session-consistent evaluations:
services.AddScoped<IFeatureManagerSnapshot, FeatureManagerSnapshot>();
3. iPadOS Considerations
Store user/country mappings in secure local storage (Keychain)
Use background fetch for filter updates
Implement offline cache with SQLite[Previous SQLite answers]
Validation Matrix
Scenario Country Enabled User Disabled User Override Result
1 Yes (US) No No Enabled
2 Yes (CA) Yes No Disabled
3 No No Yes Enabled
4 No Yes Yes Enabled
This solution meets your requirements by:
1. Prioritizing user-level overrides (irrespective of country)
2. Enforcing country-level enables unless explicitly user-disabled
3. Working offline with cached configuration [19] [18]
4. Complying with iPadOS 18+ security requirements[Previous answers]
For production use, add telemetry to track filter hit rates and validation errors [17] [18] .
⁂
1. https://learn.foundersandcoders.com/learn/database/
2. https://sqlite.org/forum/info/0f13325042dff949bc28570d6dda7559c2dede2bdb34d0b70b67523a920
4ccdb
3. https://docs.docker.com/get-started/workshop/05_persisting_data/
4. https://www.powersync.com/blog/sqlite-persistence-on-the-web
5. https://www.nuget.org/packages/Microsoft.EntityFrameworkCore.Sqlite/8.0.8
6. https://www.xanthium.in/cross-platform-create-connect-update-sqlite3-database-using-csharp-dotnet
-platform
7. https://stackoverflow.com/questions/67992995/where-to-put-sqlite-database-on-ipad
8. https://stackoverflow.com/questions/9346760/where-should-i-store-the-sqlite-db-for-my-iphone-app
9. https://stackoverflow.com/questions/79241222/cant-build-deploy-net8-maui-app-with-sqlite-net-sqlci
pher-1-9-172-using-vs
10. https://github.com/praeclarum/sqlite-net/issues/1207
11. https://learn.microsoft.com/en-us/answers/questions/2069665/maui-and-ios-18
12. https://dzone.com/articles/feature-flags-in-net-8-and-azure
13. https://learn.microsoft.com/en-us/azure/azure-app-configuration/quickstart-aspnet-core-app
14. https://www.reddit.com/r/dotnetMAUI/comments/1ad57vd/best_approach_to_synchronizing_data_for_of
fline/
15. https://gist.github.com/SteveSandersonMS/ba16f6bb6934842d78c89ab5314f4b56
16. https://softwareengineering.stackexchange.com/questions/171342/syncing-objects-to-a-remote-server
-and-caching-on-local-storage
17. https://learn.microsoft.com/en-us/azure/azure-app-configuration/feature-management-dotnet-referen
ce
18. https://learn.microsoft.com/en-us/azure/azure-app-configuration/concept-feature-management
19. https://www.youtube.com/watch?v=IJ1BRSLZDgg
