On 07/02/2012 16:43, Rick Hillegas wrote:
Hi John,
This is one of many areas where Derby's dependency tracking could be
improved. I think that Derby is over-aggressive in dropping views when
you drop a column in the underlying table.As I read the SQL Standard
(part 2, section 11.19 <drop column definition>), a RESTRICTed column
drop does not need to affect views which don't reference the column.
My copy of SQL-92 has this as section 11.15, and according to General
Rules (2) in this section:
"Let VN be the name of any view that contains a reference to
column C of table T. The following <drop view statement> is
effectively executed with a current <authorization identifier>
of "_SYSTEM" and without further Access Rule checking:
DROP VIEW VN CASCADE".
This seems a bit peculiar to me, as silent unasked-for behaviour
generally leads to trouble in my experience. But it seems that this
is indeed mandated by the standard... The over-aggressive behaviour
of Derby just means you're even less sure than usual what gets hosed
automatically when you drop a column!
Thanks for pointing me to the appropriate section of a document I find
rather dense at times... :-)
------------------------------------------------------------------------
John English | My old University of Brighton home page is still here:
| http://www.cem.brighton.ac.uk/staff/je/
------------------------------------------------------------------------
