Re: our checks for read-only queries are not great

On Thu, Jan 9, 2020 at 3:07 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > Maybe the SQL standard has something to say about this?
>
> [ pokes around ... ] Yeah, it does, and I'd say it's pretty clearly
> in agreement with what Peter did, so far as DML ops go. For instance,
> this bit from SQL99's description of DELETE:
>
> 1) If the access mode of the current SQL-transaction or the access
> mode of the branch of the current SQL-transaction at the current
> SQL-connection is read-only, and T is not a temporary table,
> then an exception condition is raised: invalid transaction state
> - read-only SQL-transaction.
>
> UPDATE and INSERT say the same. (I didn't look at later spec versions,
> since Peter's 2003 commit was probably based on SQL99.)

OK. That's good to know.

> You could argue about exactly how to extend that to non-spec
> utility commands, but for the most part allowing them seems
> to make sense if DML is allowed.

But I think we allow them on all tables, not just temp tables, so I
don't think I understand this argument.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company