Preserve consecutive Event ordering in EF inserts

[BramKraai]

The EF Core DbContext.Add and DbContext.AddRange methods sort entries alphabetically instead of preserving insertion order. This leads to violations in the ConsecutiveIndex constraint in Postgres. This error does not happen in SQL Server. (why not?)

By referencing the previous Event in Applied Events, EF Core can figure out the dependencies between events and correctly preserve the insertion order.

Alternative strategies to fix this issue:

• Call DbContext.Add + DbContext.SaveChangesAsync for every added Event
  • Very slow, since it requires many round trips to the Database
• Use a Bulk Insert Library that does preserve insertion order
  • We have to keep the licensing and maintenance in mind when choosing to do so
• Write custom Bulk Insert Library that does preserve insertion order
  • Will fix this issue and improve performance, but requires many tests to cover all cases.
• Investigate why SQL Server does work and see if the same configuration can be applied for Postgres

[nielsdisveld]

Investigate why SQL Server does work and see if the same configuration can be applied for Postgres

I did a simple test with adding 4 events in a single transaction and watched the logs for the generated SQL commands by EF.

When using Postgres the generated SQL insert commands seem to be a single command for every row.

While for SQL Server the generated commands seem a bit smarter since they try to have a single insert command for multiple rows. (In my example 1 command for 1 row and another command for 3 rows)

After some more testing: It is also an issue for SQL Server.