On 10.10.2012 03:45, Peter Eisentraut wrote:
About that plugins directory ($libdir/plugins) ... I don't think we ever really got that to work sensibly. I don't remember the original design discussion, but I have seen a number of explanations offered over the years. It's not clear who decides what to put in there (plugin author, packager, DBA?), how to put it there (move it, copy it, symlink it? -- no support in pgxs), and based on what criteria.
Yeah, it would be good to clarify that. It was originally added for the pldebugger module (http://archives.postgresql.org/pgsql-hackers/2006-07/msg00803.php), but I couldn't find any discussion on the decision to create a new 'plugins' directory.
It was never quite enough for pldebugger, as you still needed to add it to shared_preload_libraries for it to work, at least if you wanted to get the full functionality. The installation procedure in the README clearly instructs to add it to shared_preload_libraries, it doesn't say anything about local_preload_libraries. I recently refactored pldebugger to not install in the plugins directory anymore, it now just drops it in $libdir.
It would seem to be much more in the spirit of things to simply list the allowed plugins in a GUC variable, like some_clever_name_here = $libdir/this, $libdir/that but there is probably a reason why this wasn't done that way in the first place.
I think the idea was that plugins directory would be easier for users/admins. I agree that a GUC like above feels more natural.
Now that we support include-directories in postgresql.conf, you could put a "mylib.conf" file in the include directory that contains the above line, if you want to enable/disable a module just by moving things around in the filesystem (after configuring an include directory in postgresql.conf). But actually, you can't, because there's no way to append to a setting, you can only override. That's an obvious missing feature in the include mechanism. Even ignoring the plugins directory, it would be nice to be able to append libraries to shared_preload_libraries.
- Heikki -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
