Re: trigger example for plsample - Mailing list pgsql-hackers

From Fabrízio de Royes Mello
Subject Re: trigger example for plsample
Date
Msg-id CAFcNs+oL581ToM-2VoJBXmL8TOnAsWjsQbfeXnXmCwsv4a05ow@mail.gmail.com
Whole thread Raw
In response to Re: trigger example for plsample  (Mark Wong <markwkm@gmail.com>)
List pgsql-hackers

On Wed, Apr 6, 2022 at 5:44 PM Mark Wong <markwkm@gmail.com> wrote:
>
> On Thu, Mar 10, 2022 at 06:36:44PM -0500, Chapman Flack wrote:
> > On 03/02/22 15:12, Mark Wong wrote:
> >
> > > I've attached v2, which reduces the output:
> > >
> > > * Removing the notices for the text body, and the "compile" message.
> > > * Replaced the notice for "compile" message with a comment as a
> > >   placeholder for where a compiling code or checking a cache may go.
> > > * Reducing the number of rows inserted into the table, thus reducing
> > >   the number of notice messages about which code path is taken.
> >
> > I think the simplifying assumption of a simple interpreted language allows
> > a lot more of this code to go away. I mean more or less that whole first
> > PG_TRY...PG_END_TRY block, which could be replaced with a comment saying
> > something like
> >
> >   The source text may be augmented here, such as by wrapping it as the
> >   body of a function in the target language, prefixing a parameter list
> >   with names like TD_name, TD_relid, TD_table_name, TD_table_schema,
> >   TD_event, TD_when, TD_level, TD_NEW, TD_OLD, and args, using whatever
> >   types in the target language are convenient. The augmented text can be
> >   cached in a longer-lived memory context, or, if the target language uses
> >   a compilation step, that can be done here, caching the result of the
> >   compilation.
> >
> > That would leave only the later PG_TRY block where the function gets
> > "executed". That could stay largely as is, but should probably also have
> > a comment within it, something like
> >
> >   Here the function (the possibly-augmented source text, or the result
> >   of compilation if the target language uses such a step) should be
> >   executed, after binding these values from the TriggerData struct to
> >   the expected parameters.
> >
> > That should make the example shorter and clearer, and preserve the output
> > tested by the regression test. Trying to show much more than that involves
> > assumptions about what the PL's target language syntax looks like, how its
> > execution engine works and parameters are bound, and so on, and that is
> > likely to just be distracting, IMV.
>
> I think I've applied all of these suggestions and attached a new patch.
>

Cool... I also have a look into the code. To me everything is also ok!!!

Regards,

--
Fabrízio de Royes Mello

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