How to write universal optimistic concurrency Timestamp column that works with SQL Server and with Postgresql

We need to support both databases: SQL Server and Postgresql. For optimistic concurrency we use a [Timestamp] column.

For SQL Server this code works:

public class DbEntity
{
	...
	[Timestamp]
	public byte[] Timestamp { get; set; }
	...
}

In the database, this field is mapped to:

[Timestamp] [timestamp] NOT NULL

For Postgresql we need something like this:

public class DbEntity
{
	...
	[Timestamp]
    public uint Version { get; set; }
	...
}

without column in database, because xmin system column used - https://www.npgsql.org/efcore/modeling/concurrency.html?tabs=data-annotations

It is possible to write universal entities that works with both databases? I want to write them once, and do not support 2 applications or 2 branches in source control.

You can use have both properties on your .NET type and vary the EF model configuration based on the provider being used, and ignore the property for the other databases:

public class Blog
{
    public int Id { get; set; }

    [Timestamp]
    public byte[] Timestamp { get; set; }

    [Timestamp]
    public uint Version { get; set; }
}

// In the model configuration:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    if (Database.IsSqlServer())
    {
        modelBuilder.Entity<Blog>().Ignore(b => b.Version);
    }
    else if (Database.IsNpgsql())
    {
        modelBuilder.Entity<Blog>().Ignore(b => b.Timestamp);
    }
}