Entity Framework code first auto migration not working with Oracle database

Question

I have some issue with an Oracle database. When I run my Windows Forms application using Entity Framework 6 to apply all database related changes to the Oracle database, I get this error:

Automatic migrations that affect the location of the migrations history system table (such as default schema changes) are not supported.
Please use code-based migrations for operations that affect the location of the migrations history system table.

Oracle database version: "Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production Version 18.4.0.0.0 "

I am using a code-first approach with auto migration enabled. This code first approach working perfectly when I connect to SQL Server database ( note : SQL Server database connection only for cross check) but have this issue with Oracle.

What I tried from my side

I added code-based migration script ie Add-Migration CreateNewDB and then applied this migration to Oracle database and it works.

But I want to auto-update the database and apply any changes to the Oracle database which is still not working automatically (auto migration). Currently I need to create a code-based migration and apply that to Oracle database every time.

Sample code on model create

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {

            base.OnModelCreating(modelBuilder);
            
            modelBuilder.HasDefaultSchema("PDBADMIN");
       
       
            modelBuilder.Entity<ADHOCCHECK>()
                .Property(e => e.sortrev)
                .IsUnicode(false);

            modelBuilder.Entity<ADHOCCONSTRAINT>()
                .Property(e => e.fldtype)
                .IsUnicode(false);

            modelBuilder.Entity<ADHOCCONSTRAINT>()
                .Property(e => e.fldstr1)
                .IsUnicode(false);
                }

Any help would be appreciated.

Thanks!

Answer 1

You are changing your schema to PDBADMIN in this line modelBuilder.HasDefaultSchema("PDBADMIN"); . Unfortunately, you can't use automatic migrations with the Oracle provider using a custom schema name.

From Oracle's documentation

Code First Automatic Migrations is limited to working with the dbo schema only . Due to this limitation it is recommended to use code-based migrations, that is, add explicit migrations through the Add-Migration command.

So you have to either use the default schema name dbo , or disable automatic migrations and use code based migrations.

In my personal opinion, even if you hadn't come across this particular problem with the Oracle provider, I would strongly recommend usindg code based migrations anyway.

It's also the official recommendation when working on a team:

You can intersperse automatic and code-based migrations but this is not recommended in team development scenarios. If you are part of a team of developers that use source control you should either use purely automatic migrations or purely code-based migrations. Given the limitations of automatic migrations we recommend using code-based migrations in team environments.