Why does db.select<T> is so slow when the model inherits from AuditBase?

The slow performance you're experiencing while using db.Select<T> is likely due to its implementation which employs a database-agnostic abstraction layer of the OrmLite ORM library. This means it doesn't directly interact with your specific SQLite database, but rather delegates this task to an underlying data access API that can handle various databases.

The problematic operation here is fetching all records from the database which might be slower on a small table due to its nature and efficiency considerations. In contrast, operations like insert or update are faster as they don't have to retrieve every record for processing.

Your Record model inherits from AuditBase, which contains audit fields such as CreatedBy, ModifiedBy, CreatedDate, ModifiedDate, making the number of records and therefore the execution time longer. These extra columns might add a significant overhead to your database operations, especially on smaller tables like yours (with 100 records).

To resolve this issue, you could try to separate these audit fields from your base model class or use a more efficient method for managing them in the first place, instead of relying solely on inheritance. This would not only speed up database operations but also maintain a clean and simpler model design.

Also consider whether using an embedded SQLite database like SQLitePCLRaw.bundle_e_sqlite3 or a standalone installation of SQLite for .NET is necessary in your project, as the performance might be impacted by this difference due to its nature and potential compatibility issues with other libraries.

When a model inherits from AuditBase, ORMLite adds extra columns to the table definition: CreatedDate, CreatedById, ModifiedDate, ModifiedById. If these columns are not indexed, selecting all records triggers a full table scan. To fix the issue, add indexes to these columns:

if (db.CreateTableIfNotExists<Record>())
{
    foreach (var columnName in new[] { "CreatedDate", "CreatedById", "ModifiedDate", "ModifiedById" })
    {
        db.CreateIndex(typeof(Record), columnName, false);
    }
    
    for (int i = 0; i < 100; i++)
    {
        db.Insert(new Record()
        {
            Name = $"Name {i}" ,
            
            CreatedBy =  "TEST",
            ModifiedBy = "TEST",
            CreatedDate = DateTime.Now,
            ModifiedDate = DateTime.Now
                                     
        });
    }
}

The slowness you're experiencing when using db.Select<Record>() with the model inheriting from AuditBase is likely due to the additional fields that come with the AuditBase inheritance.

The AuditBase class probably contains additional fields such as CreatedBy, ModifiedBy, CreatedDate, and ModifiedDate. When you fetch records from the database, these additional fields will also be fetched and deserialized into memory for each record. This results in more data being transferred between the database and application, which can significantly impact performance, especially for larger result sets.

To verify this, you could try creating a separate select query that only retrieves the necessary columns for your use case (the ones not present in the AuditBase class):

using (var db = appHost.Resolve<IDbConnectionFactory>().Open())
{
    if (db.CreateTableIfNotExists<Record>())
    {
        // ... (populate data)
    }

    var stopwatch = new Stopwatch();
    stopwatch.Start();
    
    var recordsWithNeededColumns = db.Query<Record, Record>(x => x.Name != null);

    var loadTime = stopwatch.ElapsedMilliseconds;
    Console.WriteLine($"Took {loadTime}ms to load {recordsWithNeededColumns.Count()} records");
    
    return new HelloResponse { Result = $"Hello, {request.Name}!" };
}

This way, the query only retrieves the Name column, and you will see if the performance issue is due to the additional columns in your inheritance model. If this improves the performance significantly, it might be a good idea to consider creating a separate DTO (Data Transfer Object) for fetching data specifically for this use case without the unnecessary fields. This can be achieved using AutoQuery or similar approaches.

The issue you're experiencing is likely due to the fact that the AuditBase class is adding additional fields that need to be populated and selected from the database. When you inherit from AuditBase, your Record class will have additional fields like CreatedBy, ModifiedBy, CreatedDate, and ModifiedDate. These additional fields will require more time to be populated from the database, leading to slower query times.

To confirm this, you can try running a similar query using a Record class that does not inherit from AuditBase. You should see that the query time is significantly faster.

If you need to continue using AuditBase and want to improve query performance, there are a few things you can try:

1. Use manual mapping: Instead of using OrmLite's automatic mapping feature, you can use manual mapping to map your Record class to the database table. This will allow you to select only the fields that you need, reducing the amount of data that needs to be queried from the database.
2. Use a view or stored procedure: If you frequently need to query a large number of records, you can create a view or stored procedure that selects only the fields that you need. This will allow you to avoid querying the additional fields in AuditBase, improving query performance.
3. Optimize your database: You can also try optimizing your SQLite database by indexing the fields that are frequently queried. This can help improve query performance, especially for large datasets.

Here's an example of how you can use manual mapping to improve query performance:

var records = db.Select<Record>(q => q.Select(x => new { x.Id, x.Name }));

In this example, we're using manual mapping to select only the Id and Name fields from the Record table. This will reduce the amount of data that needs to be queried from the database, improving query performance.

I hope this helps! Let me know if you have any other questions.

The slow performance when using db.select<T> when the model inherits from AuditBase has several reasons:

1. Increased overhead: The AuditBase class adds additional metadata and functionality that can increase the amount of processing required for the query.
2. Complex table structure: AuditBase might add indexes and other internal data structures, which can affect the query execution.
3. Reflection overhead: Selecting through db.Select() requires reflection, which can add significant overhead to the query execution.
4. Caching: The database may be caching the results, and the query might be performing additional checks or operations on the cache, leading to increased execution time.

In contrast, when the model does not inherit from AuditBase, the database does not add these extra elements and focuses solely on the data, resulting in a much faster performance.

Here are some potential solutions you can consider:

• Use a different database: If performance is a major concern, try using a different database that might be optimized for performance, such as Entity Framework or NHibernate.
• Reduce data read: If you can, modify the logic to retrieve only the necessary data from the Record model.
• Optimize the query: You can try optimizing the query to improve its execution time. For example, you can use the select clause to explicitly select only the required columns, and you can use indexes to improve the database's ability to execute the query.
• **Use the AsNoTracking()`` method**: The AsNoTracking()` method can be used to prevent EF from tracking the changes made to the entities during the query. This can be useful if you only need the results of the query and do not need to track the changes made to the entities.

I'm not able to repro this perf issue, I've created 2 programs, 1 which inherits AuditBase as done in this example at: https://gist.cafe/fe8d04617ee1b061f24b0d8d56948119 Which shows it completes in . Whilst another example which replaces DateTime properties with long's to store Unix Timestamps to avoid DateTime conversions during Select at: https://gist.cafe/a7c55a56842899a1ce34f11456027a9b Which completes in roughly the same time at .

The AuditBase class is responsible for adding auditing information to your models. When inheriting from this class, it adds additional columns to the table, such as CreatedBy, ModifiedBy, CreatedDate, and ModifiedDate. This can cause the table to be slower when retrieving data, especially if you have a large number of records in the table.

To optimize the performance of your query, you can try the following:

1. Use AuditBase only for the models that need auditing information, and avoid inheriting it from other classes or models that do not require this functionality.
2. Consider using a smaller data type for the auditing columns, such as nvarchar(100) instead of nvarchar(max). This can help reduce storage space and improve query performance.
3. If possible, try to filter your queries by the AuditBase class or only retrieve specific columns that you need from the table. This can help reduce the amount of data that needs to be retrieved, which can improve query performance.
4. Consider using a different database management system or database engine if the current one is not performing well. Some databases are optimized for certain types of queries and may perform better for your use case.
5. If none of the above solutions work, you may need to consider scaling up your infrastructure by adding more resources, such as CPU or memory, to handle larger volumes of data and improve query performance.

Hello there. Thank you for asking this question. Let's take a closer look at your issue. I assume you're using Db.Select<Record>(), which selects all the records from the Record table. The query looks like this:

db.Select(record) as Row => (Name, CreatedBy, ModifiedBy, DateCreated, ModifedDate)

I would recommend adding :memory: to your SQLite database if you have enough RAM and can't connect to a local server. This will speed up the performance since it bypasses disk I/O. Here's how you can do that with our AutoQueryDb field in MyServices.

public class MyServices : Service
{
  public IAutoQueryDb AutoQuery { get; set; } = null!;

  [DependentOn]
  public Db.DbService()
  {
    // connect to database 
   }

  public object Any(Hello request)
  {
    var sw = new Stopwatch();

    sw.Start();

     // create the in-memory data source with ":memory:" as a parameter.
     Db.AutoQuery(db, ":memory")

     if (AutoQueryDb.IsLoaded())
    { 

        auto recordSet = AutoQueryDb.All()
        .ToSelect() // converts it to query 

        // Do some stuff here using your code. For example:  recordSet.Where(r => r.Name.Contains(request.name).ThenBy(c => c))

    } else 
       { Console.WriteLine("There's an error loading the data, please try again later"); return HelloResponse(); } 

      var loadTime = sw.ElapsedMilliseconds;
       Console.WriteLine($"Took {loadTime}ms to load {recordSet.Count} records in memory") ; // or ":memory:" will be replaced with the actual path where it is created.

}

By adding :memory: parameter, you can use a SQLite database stored locally on your computer instead of over a server. This avoids the long load time for loading data from a remote location to your local machine and then accessing them in memory. You can replace "Hello" with any value or expression that involves accessing these records, and then return that as the Result value in your HelloResponse. Let me know if you have any further questions or issues.

It is taking so long because the code uses an AutoQuery property on the MyServices class. This allows for faster querying of data in memory or in a database. In this case, the MyServices class has an AutoQuery property that is set to null! This means that there is no data available to use for auto-query purposes. As such, when the code attempts to query data using the AutoQuery property on the MyServices class, it will receive an error because there is no data available to use for auto-query purposes.

Answer:

The db.select<T> method is slow when the model inherits from AuditBase because of the additional overhead associated with Auditing functionality.

Auditing Functionality:

• Auditing entities: AuditBase classes have additional properties such as CreatedBy, ModifiedBy, and CreatedDate that store auditing information.
• Auditing events: Every change to an audited entity triggers an auditing event, which can result in a significant amount of overhead.
• Event logging: Auditing events are typically logged in a separate table, which can increase the database write operations.

Impact on Performance:

The above overhead can significantly impact the performance of db.select<T> operations, especially for large tables. In the given scenario, the table has 100 records, which may not seem like a large number, but the Auditing functionality adds a considerable amount of overhead, resulting in a slow query.

Solution:

There are several ways to improve the performance of db.select<T> when the model inherits from AuditBase:

• Disable auditing: If you don't need auditing functionality, you can disable it by setting AuditBase.Enabled to false.
• Use a different database engine: SQLite may not be the best choice for high-performance auditing, as it can be slow for large write operations. Consider using a relational database engine such as PostgreSQL or MySQL instead.
• Optimize auditing events: If you need auditing functionality but want to minimize the overhead, you can optimize the auditing events by minimizing the amount of data stored for each event.

Additional Notes:

• The Stopwatch class is used to measure the time taken for the query.
• The Db object is assumed to be an instance of an IDbContext interface that provides access to the database.
• The AutoQueryDb property is not used in this code snippet, so it is not clear what its purpose is.

Conclusion:

In summary, the slow performance of db.select<T> when the model inherits from AuditBase is due to the additional overhead associated with Auditing functionality. To improve performance, consider disabling auditing, using a different database engine, or optimizing auditing events.