Question

I am working on a program that is supposed to insert hundreds of rows to the database per run.

The problem is that once the inserted data is wrong, how can we recover from that run? Currently I only have a log file (I created the format), which records the raw data get inserted (no metadata nor primary keys). Is there a way we can create a log that database can understand it, and once we want to undo the insertion we feed the database with that log file.

Or, if there is alternative mechanism of undoing an operation from a program, kindly let me know, thanks.

Answer 1

The fact, that this is only hundreds of rows, makes it succeptible to the great-grandmother of all undo mechanisms:

• have a table importruns with a row for each run you do. I assume it has an integer auto-increment PK
• add a field to your data table, that identifies carries the PK of the import run
• for insert-only runs, you just need to DELETE FROM sometable WHERE importid=$whatever

If you also have replace/update imports, go one step further

• for each data table have a corresponding table, that has one field more: superseededby
• for each row you update/replace, place an original copy of the row in this table plus the import id in superseededby
• to revert, you now have to add INSERT INTO originaltable SELECT * FROM superseededtable WHERE superseededby=$whatever

You can clean up superseededtable for known-good imports, to make sure, storage doesn’t grow unlimited.