On 11/6/14, 2:58 AM, Simon Riggs wrote:
On 5 November 2014 21:15, Peter Eisentraut <pete...@gmx.net> wrote:
On 10/31/14 6:19 AM, Simon Riggs wrote:
Various ways of tweaking Foreign Keys are suggested that are helpful
for larger databases.
* INITIALLY NOT ENFORCED
FK created, but is not enforced during DML.
Will be/Must be marked NOT VALID when first created.
We can run a VALIDATE on the constraint at any time; if it passes the
check it is marked VALID and presumed to stay that way until the next
VALIDATE run.
Does that mean the FK would become invalid after every DML operation,
until you expicitly revalidate it? Is that practical?
I think so.
We store the validity on the relcache entry.
Constraint would add a statement-level after trigger for insert,
update, delete and trigger, which issues a relcache invalidation if
the state was marked valid. Marked as deferrable initially deferred.
I don't think you'd need to invalidate on insert, or on an update that didn't
touch a referenced key.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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