On Tue, Oct 11, 2011 at 08:08:32PM -0400, Josh Kupershmidt wrote: > On Mon, Oct 10, 2011 at 1:18 PM, Robert Haas <robertmh...@gmail.com> wrote: > > On Thu, Aug 11, 2011 at 11:43 PM, Josh Kupershmidt <schmi...@gmail.com> > > wrote: > >> I think the doc section about using lo_manage() as a trigger: > >> http://www.postgresql.org/docs/current/static/lo.html > >> > >> could have its example tweaked to use a column-level BEFORE UPDATE > >> trigger, so as to save unnecessary trigger firings. Something like the > >> attached, perhaps? > > > > Uh, wow. That syntax is horribly surprising, isn't it? My eyes want > > to parse it as: > > > > BEFORE (UPDATE OF raster) OR (DELETE ON image) > > > > ...which is totally wrong. > > Yeah, the syntax we have is really confusing. I notice this tidbit on that > page: > > | The ability to specify multiple actions for a single trigger using OR > | is a PostgreSQL extension of the SQL standard. > > Maybe the folks dreaming up the SQL standard are sharper than they get > credit for. > > > I'm inclined to think that maybe we should leave that example as-is, > > and maybe add the variant you're proposing as a second example, > > showing how the basic version can be refined. > > The nice thing about keeping the example the way it is, is that it's > pretty simple to understand, and maybe adding the second slightly more > complicated example would just confuse things. We could just add in a > blurb like this at the end of "How to Use It": > > You may wish to restrict the trigger > to only fire upon UPDATEs of the <type>lo</> column(s) in the table by > specifying the column name via BEFORE UPDATE OF > <replaceable class="parameter">column_name</replaceable>.
I think I like that idea so I used your text instead of the full new example. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
