Hi Darafei, On Sat, Jul 14, 2018 at 3:53 AM, Darafei "Komяpa" Praliaskouski < [email protected]> wrote:
> Hi Pavan, > > вт, 10 июл. 2018 г. в 12:48, Pavan Deolasee <[email protected]>: > >> >> On Tue, Jul 10, 2018 at 12:22 PM, Darafei "Komяpa" Praliaskouski < >> [email protected]> wrote: >> >>> >>> What you can try is to short-circuit ST_Expand to ST_Buffer for now. >>> It's more expensive computationally, but for most practical use cases the >>> box it produces should be similar to that of ST_Expand, and serialized >>> geometry should produce the same box on both sides of serialization. >>> >>> >> >> Thanks for the tip. That seems to do the trick. Apart from the >> performance impact, can this cause any regression? FWIW PostGIS regression >> tests does not show any new failure, but anything specific I should test? >> With regard to performance impact, could it be material? And if so, in what >> circumstances? >> > > I've created a ticket for your issue so we can do something about it. > https://trac.osgeo.org/postgis/ticket/4122#ticket > > Please check if everything's right in it. > Yes, it looks alright. > > You said you're willing to write a patch. An approach I see now would be > is to take box3d->geometry code from here: > > https://github.com/postgis/postgis/blob/587badb8cca5b59f734c1a0d689024 > f0287bc47b/postgis/lwgeom_box3d.c#L183 > > Then, replace the POLYGON, LINESTRING and so on generation with generation > of MULTIPOINT with just points. In geography lines are curvy, so > unfortunately drawing a 3D shape with only endpoints will be too wavy to be > correct. > Transform box coords to normal using cart2geog just like here: > > https://github.com/postgis/postgis/blob/fce3e121f3726aabfe8cfc6e4d98f3 > 1c6713c0f4/liblwgeom/g_serialized.c#L275 > > All this new code should go to a function here: > https://github.com/postgis/postgis/blob/f1f6de48cd205e620e56aca8157080 > d7a34a6888/postgis/geography_measurement.c#L479 > > A PR can be sent on github, https://github.com/postgis/postgis - or post > a patch in any convenient format. > Ok, thanks for the pointers. I will work on this, but the priority has gone down a bit for me thanks to the workaround you proposed above, which is working fine for the XL user. Thanks, Pavan -- Pavan Deolasee http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
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