the maintainer believe this is safe, but this is a very complex
area and reality may turn out to be different. If **ANYHTING** at
all seems out of place, please file a report at once
+ - The unique constraint info (including the primary key columns) is no
+ longer shared between related (class and schema-level) ResultSource
+ instances
- Neither exception_action() nor $SIG{__DIE__} handlers are invoked
on recoverable errors. This ensures that the retry logic is fully
insulated from changes in control flow, as the handlers are only