No, X$ tables exist even before a database is created -> they are mostly instance related structures, not database or data dictionary ones. Do a startup nomount and select from x$ksuse or even dual for example and you see. You just can't select from these x$ tables which want to read physical database structures when database doesn't exist or isn't mounted/open. The translation of SGA memory structures to a returnable row set is pure C code, I think.
Or if you can point me to these "certain catalog scripts", I'd be glad to read them :O) But yes, about the "fixed area" I wasn't entirely correct at first. The Oracle term "fixed_sga" is really fixed, that it's size shouln't change if you don't relink of patch your executables. x$version contents are probably in fixed_sga. The other stuff, like enqueues goes to variable SGA (shared pool), but still many memory structures are not dynamic - they're allocated during startup and will remain the same during the lifetime of an instance. Tanel. ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Monday, September 29, 2003 9:24 PM > With all due respect, I don't believe that it is a fixed area. > You can create X$ tables by running certain catalog scripts. I believe > that the description of X$ tables is located logically close to the > description of the data dictionary, which would mean shared pool, not > the fixed one. Now, can we get back to bears? > > -- > Mladen Gogala > Oracle DBA > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > > Behalf Of Tanel Poder > > Sent: Monday, September 29, 2003 1:45 PM > > To: Multiple recipients of list ORACLE-L > > Subject: Re: x$ constructs and memory > > > > > > > What I have not checked so far is how an ALTER SYSTEM > > increasing a > > parameter affects the SGA. In practice it's a realloc() > > (functionally speaking). It would seem reasonable to me to > > have a shared memory segment to hold all parameters which can > > by dynamically changed. I wouldn't touch it if parameters are > > decreased, but I would have to realloc it in case of a > > massive increase. Hmm, I guess that I would allow some spare > > memory initially, performance penalty would otherwise be > > severe. Which all makes the 10g dynamic rearrangement quite > > sensible ... > > > > Hi! > > > > I think the behaviour depends on which parameter you are > > changing. If you're changing shared_pool_size to higher size, > > then just additional extents of memory are allocated and heap > > header is updated. If you set sort_area_size higher, nothing > > particular happens, except some maximum is increased in UGA I > > believe and during next sort you can go up to that limit. > > Some parameters like enqueue_resources can't be changed in > > the fly, because they are fixed, they stay in fixed area of > > SGA, fixed area isn't managed as heap as I understand, it > > does not have any free or LRU lists, because it's physical > > structure remains unchanged during the lifetime of an instance. > > > > Tanel. > > > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: Tanel Poder > > INET: [EMAIL PROTECTED] > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > San Diego, California -- Mailing list and web hosting services > > --------------------------------------------------------------------- > > To REMOVE yourself from this mailing list, send an E-Mail message > > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') > > and in the message BODY, include a line containing: UNSUB > > ORACLE-L (or the name of mailing list you want to be removed > > from). You may also send the HELP command for other > > information (like subscribing). > > > > > > > Note: > This message is for the named person's use only. It may contain confidential, proprietary or legally privileged information. No confidentiality or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. Wang Trading LLC and any of its subsidiaries each reserve the right to monitor all e-mail communications through its networks. > Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorized to state them to be the views of any such entity. > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Mladen Gogala > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Tanel Poder INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
