Re: RLS + XPATH

On 10/31/22 13:37, Joshua Drake wrote:
> Team,
> 
> While on the road in Iowa visiting covered bridges I met up with an 
> amazing individual named Brent. Brent, is with a small organization 
> named: Darpa.
> 
> They are using PostgreSQL + RLS + XPATH but unfortunately the 
> performance has been less than what those who use PostgreSQL on a daily 
> basis would expect. Specifically when using RLS + XPATH, the optimizer 
> does not prefilter and will scan every row. This has taken their 
> previous queries on another database from sub second, to 25+ seconds on 
> PostgreSQL.
> 
> Unfortunately, we were at a covered bridge park (see attached) and 
> weren't able to get deeper into the issue. That said, I did tell him 
> that I would report the issue. Maybe there is traction, maybe there 
> isn't to get this issue fixed.


The related functions need to be marked leakproof to get decent 
performance from RLS.

-- 
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com