Re: Prepare/Execute silently discards prohibited ORDER BY values

Josh Berkus <josh@agliodbs.com> writes:
> Tested On: 9.4.1, 9.3.6
> Severity: minor
> Summary: PREPARE/EXECUTE appears to silently discard ORDER BY parameters.

> josh=# prepare foo as select * from test order by $1;
> PREPARE

I don't see anything wrong with this.  Ordering by a provably constant
expression is a no-op, not an error.

> What appears to be happening is that the prohibited parameter for ORDER
> BY is being silently discarded during EXECUTE.  At first I thought it
> might just be doing ORDER BY 'test' in the background, but that's not it:

> josh=# select * from test order by 'test';
> ERROR:  non-integer constant in ORDER BY

This error is purely a syntactic restriction, not a semantic one.
There's nothing that will stop you from ordering by, say, "cos(0)";
and the planner will throw that away too.

            regards, tom lane