Re: Feature improvement: can we add queryId for pg_catalog.pg_stat_activity view?

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Mar 15, 2019 at 9:50 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> pg_stat_statements has a notion of query ID, but that notion might be
>> quite inappropriate for other usages, which is why it's an extension
>> and not core.

> Having written an extension that also wanted a query ID, I disagree
> with this position.

[ shrug... ] The fact remains that pg_stat_statements's definition is
pretty lame. There's a lot of judgment calls in which query fields
it chooses to examine or ignore, and there's been no attempt at all
to make the ID PG-version-independent, and I rather doubt that it's
platform-independent either. Nor will the IDs survive a dump/reload
even on the same server, since object OIDs will likely change.

These things are OK, or at least mostly tolerable, for pg_stat_statements'
usage ... but I don't think it's a good idea to have the core code
dictating that definition to all extensions. Right now, if you have
an extension that needs some other query-ID definition, you can do it,
you just can't run that extension alongside pg_stat_statements.
But you'll be out of luck if the core code starts filling that field.

I'd be happier about having the core code compute a query ID if we
had a definition that was not so obviously slapped together.

regards, tom lane