[postgis-devel] liblwgeom symbols exported by postgis module

['Sandro Santilli']

On Wed, Sep 30, 2015 at 02:16:46AM -0400, Paragon Corporation wrote:

> We just
> switched in PostGIS 2.2. to have liblwgeom not versioned with same version
> number as PostGIS, and I'm beginning to regret this decision.

We actually made the versioning more equal than before.
PostGIS was always versioned as Major.Minor while liblwgeom was
versioned Major.Minor.Micro. Starting with 2.2.0, they are both
versioned after Major.Minor.

> So yes my need to be able to run PostGIS 2.1 and PostGIS 2.2 on the same
> Postgres instance, IS a developer need.  If I can't do that without jumping
> thru hoops, then many PostGIS users are screwed
> Because it means we less sure we didn't break things.

I understand that the only way to do this with with dynamic linking
is by versioning each symbol. Should be a simple linker switch added
to the link line (at least on Linux).

> Then later they upgrade their PostGIS 2.1.8 to PostGIS 2.1.9  (the liblwgeom
> is newer than the PostGIS 2.2.0), is it okay 2.2.0 is using this 2.1.9 one.
> I cringe at the thought.

This is a non-issue because PostGIS-2.2 will be linking against
liblwgeom-2.2 while PostGIS-2.1 will be linking against liblwgeom-2.1.

> I'm not sure what benefits you are talking about.  I see only costs, not
> benefits.  Strk may see benefits.  I don't.  My packaging job has gotten a
> tinsy harder which I can live with if Sandro gains something from it.

There are free software projets out there that would like to use the
great functionality of PostGIS w/out the cost of PostgreSQL.
Namely: spatialite, QGIS, GDAL.

Also, postgis-dependent extensions could be written much more easily
(like the FINELTRA one).

> Again sorry guys.  I didn't eman to come out being so antagonistic about
> this whole thing, I just don't think we enough bandwidth for the inherited
> costs of this break.

I'm not aware of any internal regression due to the liblwgeom becoming
more autonomous. The ticket we're talking about is just an obstacle for
external use of liblwgeom, which I understand you don't want to personally
work on removing (fine by that).

--strk; 

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