Re: POC: Extension for adding distributed tracing - pg_tracing

On Thu, Jan 4, 2024, 16:36 Anthonin Bonnefoy
<anthonin.bonnefoy@datadoghq.com> wrote:
> > I used GUCs to set the `opentelemtery_trace_id` and `opentelemetry_span_id`.
> > These can be sent as protocol-level messages by the client driver if the
> > client driver has native trace integration enabled, in which case the user
> > doesn't need to see or care. And for other drivers, the application can use
> > `SET` or `SET LOCAL` to assign them.
>
> Emitting `SET` and `SET LOCAL` for every traced statement sounds more
> disruptive and expensive than relying on SQLCommenter. When not using
> `SET LOCAL`, the variables also need to be cleared.
> This will also introduce a lot of headaches as the `SET` themselves
> could be traced and generate spans when tracing utility statements is
> already tricky enough.

I think one hugely important benefit of using GUCs over sql comments
is, that comments and named protocol-level prepared statements cannot
be combined afaict. Since with named protocol level prepared
statements no query is sent, only arguments. So there's no place to
attach a comment too.