[postgis-devel] PgSQL Extension Dependencies

[Nicklas Avén]

Hi
Interesting idea!
That would mean some type of definition about what is the official
features? I mean ST_DWithin would be announced, but not _ST_DWithin.
So the announced feature list would correspond to the documentation?
So ether the documentation can be dependent on this announced feature
list, or we might be able to create the list from the documentation.
Have I understood the concept correct?
Or, that will not be enough with the documented features in the
announced list. Since this is about dependencies to other extensions
they might connect to lower levels.Even abi level?
Like internal functions in liblwgeom.
Is it obvious what level of features we are talking about here?
ATB
Nicklas
On Mon, 2018-10-29 at 12:36 -0700, Paul Ramsey wrote:
> Hey all,  In trying to fulfill a role as "PostGIS ambassador" to the
> PgSQL community, I took the opportunity to canvas developers at the
> EU conference last week on topics we raised during our code sprint in
> Boston last month. 
>   Dmitri Fontaine, the primary author of the extension framework, was
> very attentive to our growing need for some kind of inter-extension
> dependency mechanism and potentially a versioning mechanism. 
>   He proposed a "feature based" solution, which was almost added a
> few development cycles ago. (Scroll to the top of the chain to see
> his description of the idea.)
> 
> https://www.postgresql.org/message-id/flat/CA%2BTgmobe5awu4syu%3DUJJ6
> skRRuTpcfSGJhg7E1PemWkmGE_qOw%40mail.gmail.com#9e9066a22f8cf2a53edd92
> fb6c71f71c
> 
> This would allow a more granular way of extensions to describe the
> capabilities they offer, and for extensions to be reorganized over
> time. For example, right now "postgis" provides "geometry",
> "geography" and "raster". After 3.0, "postgis" will provide
> "geometry" and "geography", and "postgis_raster" will provide
> "raster" and require "geometry". So there is a dependency
> relationship between "postgis_raster" and "postgis" and the
> granularity of the features allows them to be moved around between
> extensions: a program that required "raster" would still work even
> after the extension re-organization, because the "raster" feature
> would still be there, just in a different extension.
> 
> The only trouble with the feature mechanism I see is that it requires
> omniscient developers who know exactly the right granularity to
> describe features with.
> 
> Have a look at the old patch discussion and provide your feedback
> and/or detailed discussion of what you think a
> feature/dependency/version solution that would work for us might
> entail.
> 
> Thanks!
> P
> 
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