[postgis-devel] Support Functions

[Paul Norman]

On 2019-03-03 12:47 a.m., Sandro Santilli wrote:
> By enforcing use of an index are we reducing flexibility ?

Yes.

> IIRC in the topology code we call_ST_Function specifically to _avoid_
> the bounding box check. Just because we already know the inputs
> overlap, so we want to save some cycles.


I've done the same thing. What I found was an issue was not a few cycles 
to compute the bounding box overlap, but that it allowed use of index 
scans for geometries I knew intersected. I found this most common in 
queries that generated geometries with geometry modifying functions. I 
also ran into this in queries which joined against the same table 
multiple times.