Algorithms for Updating Relational Data

Question

What algorithms are known to perform the task of updating a database by inserting, updating, and deleting rows in the presence of database constraints?

More specifically

Answer 1

I wrote one once, but it's someone else's IP, so I can't go into too much detail. However, I'm willing to tell you the process that taught me how to do this. This was a tool to make a shadow copy of a customer's "database" residing on salesforce.com, written in .NET 1.1.

I started out doing it the brute-force way (create DataSet and database from schema, turn off constraints in the DataSet, iterate through each table, loading rows, ignoring errors, for rows that are not yet in the table, repeat until more rows to add, or no more errors, or no change in the number of errors, then dump the DataSet to the DataBase, until no errors, etc.).

Brute force was the starting point because it wasn't certain that we could do this at all. The "schema" of salesforce.com wasn't a true relational schema. For instance, if I remember correctly, there were some columns which were foreign keys relating to one of several parent tables.

This took forever, even while debugging. I began to notice that most of the time was being spent on handling the constraint violations in the database. I began to notice the pattern of constraint violations, as each iteration converged, slowly, toward getting all the rows saved.

All the revelations I had were due to my boredom, watching the system sit at near 100% CPU for 15-20 minutes at a time, even with a small database. "Necessity is the mother of invention", and "the prospect of waiting another 20 minutes for the same rows, tends to focus the mind", and I figured out how to speed things up by a factor of over 100.