On Fri, 2009-10-16 at 10:14 +0900, Itagaki Takahiro wrote: > Tom Lane <t...@sss.pgh.pa.us> wrote: > > > Itagaki Takahiro <itagaki.takah...@oss.ntt.co.jp> writes: > > > I think there is a benefit to provide WHEN cluase at least > > > for compatibility with other DBMSs, even through we can move > > > the expressions into the body of trigger functions. > > > > This seems to me to be a lot of code to accomplish nothing useful. > > It will always be the case that any nontrivial logic has to be done > > inside the trigger. And the compatibility argument is entirely > > pointless given the lack of compatibility in the trigger function > > itself. > > I see that WHEN cluase is not always needed, > but I think there are several benefits to have it: > > * WHEN cluase is in SQL standard. > > * We could recheck trigger conditions when NEW tuple is modified. > (not yet implemented in the patch, though) > http://archives.postgresql.org/pgsql-hackers/2009-09/msg00286.php > > * As for compatibility, it is easy for typical users to move trigger > bodies into a function, but they don't like to merge the condition > and the bodies into a function in my experience.
+1 because * It is SQL Standard * Other RDBMS support it (Oracle, DB2) * It will reduce size of in-memory pending trigger list (for large statements) and avoid invoking run-time of function handlers, important for heavier PLs (for small statements) I also support addition of INSTEAD OF triggers for first two reasons and because it may be an easier route to allow updateable views. -- Simon Riggs www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
