> On 7 Oct 2023, at 12:01, Michał Kłeczek <michal@kleczek.org> wrote:
> 
> Hi All,
> 
> Attached is a draft patch implementing LIMIT pushdown to Append and MergeAppend nodes.
> 
> This patch eliminates the need to resort to subqueries to optimise UNIONs.
> It also enables more aggressive partition pruning.
> Not sure if it causes LIMIT pushdown to foreign partitions though.
> 
> Applying this patch causes regressions in:
> - postgres_fdw tests
> - partitions tests
> 
> This is due to subsequent partition pruning applied when LIMIT is pushed down - I guess that’s a (big) win.
> 
> I would be happy to hear if the approach is sound.
> 
> Thanks,
> Michal<limit-pushdown.patch>