Re: Generalized concept of modules - Mailing list pgsql-hackers

From PFC
Subject Re: Generalized concept of modules
Date
Msg-id op.taj8sdifcigqcu@apollo13
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In response to Re: Generalized concept of modules  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Think about version API compatibility.
Suppose you have a working database on server A which uses module foo  
version 1.Some time passes, you buy another server B and install postgres on it.  
Meanwhile the module foo has evolved into version 2 which is cooler, but  
has some minor API incompatibilities.You dump the database on server A and reload it on server B. pg_dump  
issues an INSTALL MODULE which installs foo version 2 on the new server.Due to the "minor API incompatibilities", your
databasebreaks.
 
It's really cool not to pollute the dumps (and the global namespace...)  
with all the module functions, however implementing module functionality  
can be tricky.
So don't forget about versions and possible incompatibilities ; also  
versions means you might need an UPGRADE MODULE which does more than  
uninstall + reinstall. Suppose a module has created some tables for its  
use, these shouldn't be dumped when upgrading to a new version ; however  
maybe the new version will want to add a column...
Think gentoo portage, for instance.This excellent package system is a lot more evolved than the module  
system needs to be, but having a look at the feature list would be a good  
inspiration maybe.


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