Re: efficient trigger function selection?

On Tue, Apr 10, 2012 at 4:59 PM, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:

> On Tue, 2012-04-10 at 16:07 -0400, Kenneth Tilton wrote:
> > Suppose I have an RDF-style table (with columns for subject,
> > predicate, various object types, and graph) and want to have dozens or
> > even hundreds of trigger functions defined conditionally on the
> > predicate, ie "when predicate = '<your predicate here>'".
> >
> >
> > My guess is Postgres is quite efficient at determining which if any
> > trigger functions to call, but I thought I'd ask.
>
> I recommend measuring the overhead with some bogus no-op triggers; my
> guess is that it will be significant but maybe not too bad depending on
> what the rest of the application is doing.
>
> What are you trying to accomplish with so many triggers?
>

We are simulating a graph DB in Postgres and would have one RDF-like table
with columns as described above. If we want a trigger on what is
conventionally a column for "color", with pseudo-RDF we would have:

create trigger ... when predicate = 'color'

Since the graph data model reduces *everything *into so many RDF "triples",
almost every trigger function in the application would be "when predicate =
X".

well, let's see how many we really get before we panic. :)

Thx for the input.

-ken