Detached-Mapper VS EFCore.BulkExtensions

You can configure this mapper to do it for you: https://github.com/leonardoporro/Detached-Mapper

EF Core Bulk Extensions has helped me out many a day.

I have used this and found it to have everything I need. It has a dual license though but if it is for personal use you dont have to worry about that. https://github.com/borisdj/EFCore.BulkExtensions

EF Core works for me and inserting/updating several thousand records at a time. I also found this nuget that works great https://github.com/borisdj/EFCore.BulkExtensions

Using EF core with migrations. Anything that we can’t do out of the box, we can normally do with the bulk extensions (https://github.com/borisdj/EFCore.BulkExtensions). There were two specific places I had to drop back to raw SQL, one was for a specific SELECT query that needed to be optimised, the second was a stored proc doing a MERGE that we pass in a table type (upsert of 100k records)

There is however a free nuget for EF Core which supports OP's needs https://github.com/borisdj/EFCore.BulkExtensions

For EFCore v6, you're best using EFCore.BulkExtensions, to do something like this:

I've been using this library with great success: EFCore.BulkExtensions

2nd option as you're basically doing batch save changes where batch size is 100. You should put a transaction on top of all of this though and commit at the end for data integrity reasons but that's about it. Alternatively use a NuGet that can do batch save changes (Z.EntotyFramework is paid, but https://github.com/borisdj/EFCore.BulkExtensions is free).