[postgis-devel] Union/Collect/Aggregates

[Sandro Santilli]

On Mon, Apr 29, 2019 at 10:52:23AM -0700, Paul Ramsey wrote:
> So, this issue I feel is still not resolved,
> 
> https://github.com/postgis/postgis/pull/394
> 
> We've got an open ticket now now on upgrades potentially having issues
> if they use ST_Union() in aggregates. I also have an open question
> with respect to memory leaks in the case of query cancellation.
> 
> I feel like a less intrusive implementation would be to not convert
> the individual geometries to GEOS in the transfer function, but to
> collect them in an LWCOLLECTION instead, and do the work of conversion
> and processing in the final function.
> 
> This would allow us to keep the shared transfn signature and avoid the
> upgrade issues, and would also keep all the memory in the PgSQL memory
> manager right up until finalfn, so cancellation during collection
> becomes a non-issue.

Great plan!

> I'll do this work if nobody else will, gritting my teeth as I do so,
> since it's churn for a relatively rare use case (collecting more than
> 1GB of inputs for an output that will fit in less than 1GB).

Thank you Paul, but I really hope Darafei will step in and take this
burden as we need committers to be responsible for their changes
and responsive to developers community feedback.

--strk;