Thanks for the help. I did see some strange write error, but it wasn't very clear. I now realize that my external drive was full, however, Quicken never told me that. I certainly should not have zapped any of my data so that I consider a bug in the software.
Well the bottom line is that if it can't write then it should stop and not delete. I am a Software Engineer and this is definitely a bug.
UPDATED to clearly state what a program with a modern database would do.
When a database is updated and a failure
happens there isn't any telling what parts of that database will be left
inconsistent/corrupted. And in fact the most likely thing that Quicken
did when it encountered the write error is "stop". And that is
what resulted in the "delete". In other words if Quicken was in
the process of updating the database section that contained the memorized
payees, stopping the write could leave the database without links or even
corrupted links to that data. Think about it why would Quicken purposely
delete anything after a write failure? You weren't in the process of
deleting all of your memorized payees were you? So, why would Quicken
think it needed to delete your memorized payees after a failure? It wouldn't.
Database writes have to complete successfully or
else there isn't telling if they are consistent.
With a modern database if a failure occurred what a program would do call the database function to rollback the database changes. That would be done by replaying the journal file to reverse the changes that have been made. But Quicken isn't using a modern database. What's more even
if it did have such a feature it would most likely still fail. As any
write operation to fix the problem would also fail for a full drive. What would have to happen is that the disk space would have to be increased somehow, and the rollback be run manually after that was done. Or recover from a backup. Which is exactly what you should be doing with Quicken.
Note that database, say a program like Word handle
their data files quite differently.
Word most likely writes to a temporary file, and
then replaces the old file with the new one in on delete/rename operation.
Programs that write to databases write data
"in place" (in a different section of the data file). There
isn't a second data file.
Thanks professor. I'm well aware of all of that. No matter how many words you write It is still a bug.