[postgis-devel] liblwgeom symbols exported by postgis module

[Sandro Santilli]

On Wed, Sep 30, 2015 at 02:51:12AM -0400, Paragon Corporation wrote:

> I think in retrospect I was a bit over dramatic and I'm not being quite as
> inconvenienced as I thought I was.
> I think it would be a very rare occasion that we don't have the liblwgeom
> api change with each PostGIS minor release.  And sure if someone gos from
> 2.1.8 to 2.1.9 I'd want the lilbwgeom replaced for all libraries that used
> that version.
> 
> ------------------------------------------
> Strk,
> 
> Correct if I am wrong in the above assumption.

If someone goes from 2.1.8 to 2.1.9, _prior_ to run the scripts
upgrade procedure (ALTER EXTENSION or sourcing postgis_upgrade.sql)
she'll have the old scripts served by the new "postgis-2.1.so"
library, which would contain the new "liblwgeom-2.1.9.a" symbols.

If liblwgeom was linked dynamically, in the above scenario she'll have
the old scripts served by the new "postgis-2.1.so" library, which
would dynamically link to the new "liblwgeom.so.2.1.9"

I'm not sure if this confirms your assumptions.

> It's a shame Debian provides only one single postgis version, as that makes
> it very difficult for people to do a pg_upgrade.  If they were to go to
> PostgreSQL 9.5 from PostgreSQL 9.4, and you only provide a PostGIS 2.2 on
> 9.5 (and not a 2.2 on PostgreSQL 9.4) or vice versa.  They can't just do the
> soft upgrade and pg_upgrade migrate or pg_upgrade  /soft postgis upgrade.

Didn't we recently fix that need for the old library being around ?
Or do we have an open ticket describing the issue ?

> Thanks for confirming -- so yes strk -- no export, but I wouldn't bother
> touching 2.0.  2.1 maybe. 2.0 is already like 3-4 years old.  It should only
> have security patches and egregious errors.  Not sure I consider this the
> case since no one else I am aware of has run into the issue but you.

Yeah, not many people out there are developing PostgreSQL modules
dynamically linking to liblwgeom and using them in the same session
as different PostGIS versions..

--strk;

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