Change data without breaking it

By the end of this track you will have

1. Step 1A dated copy of every record your change will touch, a tag on each of those records, and three counts that agree.
2. Step 2One sentence that fences your change, a list of everything the AI noticed and left alone, and proof that it declines to cross the fence when asked.
3. Step 3A written prediction of exactly what your change will do, in numbers, and a count of your own that agrees with it.
4. Step 4The undo for your change written down, rehearsed once on test records, checked against a copy and timed.
5. Step 5The change made in batches, and one sheet where every predicted number sits beside the actual one and they agree.

The steps

Each one ends with a check you run yourself. The box is yours to tick when it passes.

1. 1
   Step 1.Take a copy before you change anything

   45 minutesOpen to everyone

   Done means

   Open the copy in a spreadsheet and type =COUNTA(A:A)-1 into an empty cell in another column, with A as the ID column. The minus one takes off the header row. Close the file without saving. Then search your system for the tag. The formula, the tag search and the filter count all return the same number, and the file name carries today's date. If any of the three differ, the copy holds a different set from the one the change will touch. You are not ready.

   The check passed
2. 2
   Step 2.Touch only what you named

   30 minutes

   Done means

   The count of records the AI says the fence allows equals your tag count from step one, to the record. You asked it to fix a Found item as part of this job, and it declined. It quoted the fence back and left the item on the list. If the counts differ, or it offered to go ahead, the fence is not in the brief the AI is reading. Put it at the very top and run the test again.

   The check passed
3. 3
   Step 3.Dry-run the bulk edit and predict the count

   60 minutes

   Done means

   Your spreadsheet number, records in the copy minus distinct values of the field you match on, equals the AI's records to archive plus the records held back by skips, to the record. The totals carry a figure for deletes, even when it is 0, and every skipped group has a reason. If the two numbers differ by one record, the prediction is not finished. Find that record.

   The check passed
4. 4
   Step 4.Practise the undo before you need it

   60 minutes

   Done means

   With the last-edited columns taken out, the comparison sheet counts 0 differences between the test copy and the records after the undo. The notes sheet says the same. The undo sits next to the copy with the rehearsal date and the minutes it took. If any cell differs, the undo is missing a step. Fix it and rehearse again on fresh test records.

   The check passed
5. 5
   Step 5.Match expected against actual before you call it done

   120 minutes

   Done means

   Every expected line on your sheet has an actual beside it that you counted yourself in the system. Every Match reads yes, or names a difference explained below it. The deleted, orphan and untagged lines all read 0. Every difference has a sentence and the IDs behind it. If a line is blank, or an actual came from the AI's report, the change is not done. It has only stopped.

   The check passed