Thread

Re: postgres_fdw prefers fast plans

Laurenz Albe <laurenz.albe@cybertec.at> — 2025-12-10T13:12:37Z

On Wed, 2025-12-10 at 15:44 +0300, Alexander Pyhalov wrote:
> There's a long-standing issue with postgres_fdw - as it uses cursors, it 
> prefers plans, optimized for fetching first rows. In bad scenarios this 
> leads to suboptimal choice of join methods (e.g. choosing nest loop over 
> hash join) on remote side. I've crafted WIP patch, which tries to fix 
> this issue. It adds FETCH ALL cursors and uses them in postgres_fdw. 
> What do you think? Should we go in this direction?

Why not simply set cursor_tuple_fraction to 1.0 in postgres_fdw sessions?

Yours,
Laurenz Albe