I'm not sure you'll be able to convince everyone that the penalty is so negligible --- any high-rate access to shared memory is potentially very expensive, see nearby threads for examples. Even if this is affordable for the debugger, what of more-invasive plugins such as the performance monitor? I think a credible general-purpose plugin design has to address the problem of enabling plugins on-the-fly.
I have no problem with your solution - I think its a very nice design.
> I don't think it could crash because there's no way to unload a plugin > (there is no UNLOAD statement, is there?). What we actually have at the moment is that you can LOAD a library again, which causes an unload of the prior version and then loading the new. I suppose this feature was intended to speed library development by letting you recompile and then update into your existing backend session. Not sure how many people are using it, but it's there ...
Right, but you still end up with a plugin loaded afterwards so no crash (of course you could do something stupid like load a new plugin with the same name that isn't really a plugin).
> Which reminds me, you haven't proposed a way to unload a shared-library. This depends on the semantics we want to assign to backend_shared_libraries --- I could imagine defining it as "if you remove an entry from the value then we'll unload that library".
That's what I was thinking too.
> How about a combination of plan A and plan B? Make > backend_load_libraries a USERSET variable, but you can't *add* libraries > outside of $libdir/plugins/ unless you are a superuser. Not sure how easy that is (ie, can we track which part of the list came from where), but if doable it'd be OK with me. We might have to split it into two list variables to make it work, and I'm not sure it's worth the complication.
The GUC assign hook would parse through backend_load_libraries...
for each library,
{
if ( the library is already loaded )
{
// it's not a new library, doesn't matter where it lives, doesn't matter if we're a superuser
load( library)
}
else
{
// it's a new entry in backed_load_libraries
if( library lives in $libdir/plugins )
load( library )
else
{
if( is_superuser())
load( library )
else
throw an error
}
}
}
We already broke them by removing the init-function name...
Right...
> Do you want me to do any of this coding? Up to you --- I can do it if you don't want to.
I'll take a stab at it... thanks for your help so far.
-- Korry
|
-- Korry Douglas [EMAIL PROTECTED] EnterpriseDB http://www.enterprisedb.com |
