Some very good suggestions where made here. What happens next? Will this end up in a TODO list where someone can "claim the task" (I'm trying to learn how the process works) ?
Kind regards, Thomas Hallgren ----- Original Message ----- From: "Tom Lane" <[EMAIL PROTECTED]> To: "Joe Conway" <[EMAIL PROTECTED]> Cc: "Peter Eisentraut" <[EMAIL PROTECTED]>; "Thomas Hallgren" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, February 06, 2004 19:15 Subject: Re: [HACKERS] Advice regarding configuration parameters > Joe Conway <[EMAIL PROTECTED]> writes: > > I like it. I wonder if we ought to have a way to "register" valid > > classes? Maybe a new guc variable in the form of a list of valid > > classes. So something like: > > There are some order-of-processing issues there, but maybe. Another > possibility is that after a shlib has finished registering its > variables, it could look for remaining placeholders matching its prefix > and issue WARNINGs about 'em (it can't realistically ERROR, probably, > but a WARNING would surely help). These are actually orthogonal checks > since one addresses the class part and the other the individual variable. > > >> And we'd have to think a little about how to handle variable values > >> that are discovered to be erroneous when we try to assign them to the > >> variable --- probably we can just drop them, but does that make the > >> semantics weird at all? > > > Maybe we can require a default value as a parameter to > > add_guc_variable() and use that? > > Well, the new GUC variable struct would include a default by definition, > and presumably that value would "bubble up" to replace any values that > are found illegal. > > The sort of semantic funny I am thinking of is like this: > * postgresql.conf contains pljava::var = somegoodvalue > * ALTER DATABASE SET supplies pljava::var = somebadvalue > For builtin variables the ALTER DATABASE value would be rejected on > sight and the end result would be that the variable contains > 'somegoodvalue'. However if we don't yet know the variable at backend > startup, 'somebadvalue' will replace 'somegoodvalue' completely, and > then when the PL actually gets loaded it will get thrown away. End > result is that the variable will have whatever its hardwired default is, > and not 'somegoodvalue' as one would wish. Even more surprising, a > subsequent SIGHUP would make it acquire 'somegoodvalue'. > > This particular case could be dealt with by forcing a rescan of > postgresql.conf after new variables are defined (I think we need only do > so if any errors are detected in assigning values), but that will not > handle everything. We don't have any way to get back overridden values > from other sources such as the postmaster command line. > > It seems likely to me that such corner cases are sufficiently bizarre to > not bother anyone, but we need to think more to make sure that there > aren't any that would bother someone. > > regards, tom lane > ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
