On Fri, Mar 7, 2008 at 9:40 PM, Bruce Momjian <[EMAIL PROTECTED]> wrote:
> > I assume don't want a TODO for this? (Suppress UPDATE no changed > columns) > I am starting to implement this. Do we want to have this trigger function in the server, or in an external module? Best regards, > > > --------------------------------------------------------------------------- > > Andrew Dunstan wrote: > > > > > > Tom Lane wrote: > > > Michael Glaesemann <[EMAIL PROTECTED]> writes: > > > > > >> What would be the disadvantages of always doing this, i.e., just > > >> making this part of the normal update path in the backend? > > >> > > > > > > (1) cycles wasted to no purpose in the vast majority of cases. > > > > > > (2) visibly inconsistent behavior for apps that pay attention > > > to ctid/xmin/etc. > > > > > > (3) visibly inconsistent behavior for apps that have AFTER triggers. > > > > > > There's enough other overhead in issuing an update (network, > > > parsing/planning/etc) that a sanely coded application should try > > > to avoid issuing no-op updates anyway. The proposed trigger is > > > just a band-aid IMHO. > > > > > > I think having it as an optional trigger is a reasonable compromise. > > > > > > > > > > > > > Right. I never proposed making this the default behaviour, for all these > > good reasons. > > > > The point about making the app try to avoid no-op updates is that this > > can impose some quite considerable code complexity on the app, > > especially where the number of updated fields is large. It's fragile and > > error-prone. A simple switch that can turn a trigger on or off will be > > nicer. Syntax support for that might be even nicer, but there appears to > > be some resistance to that, so I can easily settle for the trigger. > > > > cheers > > > > andrew > > > > ---------------------------(end of broadcast)--------------------------- > > TIP 4: Have you searched our list archives? > > > > http://archives.postgresql.org > > -- > Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us > EnterpriseDB http://postgres.enterprisedb.com > > + If your life is a hard drive, Christ can be your backup. + > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers > -- [EMAIL PROTECTED] [EMAIL PROTECTED] gmail | hotmail | indiatimes | yahoo }.com EnterpriseDB http://www.enterprisedb.com 17° 29' 34.37"N, 78° 30' 59.76"E - Hyderabad * 18° 32' 57.25"N, 73° 56' 25.42"E - Pune 37° 47' 19.72"N, 122° 24' 1.69" W - San Francisco http://gurjeet.frihost.net Mail sent from my BlackLaptop device
