Comments as ever...
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Opinions expressed are my own, and not those of Oracle Corporation
Oracle DBA Resources: http://www.geocities.com/howardjr2000
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"Reinier" <Reinier_Dickhout_at_hetnet.nl> wrote in message
news:#XA5Q8lOAHA.335_at_net003s...
> Maybe there is a little confusion about terminology here. If I read yor
post
> correctly you want two instances on one machine. Or you can say two
> different databases. A database is ususally consider to be the total of
> datafiles, control files etc.. (I'm not saying this is right however, not
> saying it's wrong either, just can't think of a good way to describe it
> myself) whereas an instance is usually consider to be the up and running
> version of a database (you bring the database down, when down still a
> database, but you connect to an idle instance when your database is
down...
> still with me?)
Why does this cause confusion? I can't think of a simpler point for anyone
wanting to work with Oracle to grasp... and I'm not particularly including
you in that comment, since you have actually got the right answers.
An Instance is the set of memory structures that manages a database (SGA
plus background processes)
A Database is a set of Control Files+Data Files+Redo Logs.
ORACLE_SID is merely an environment variable that is used to name each
Instance just before it is created.
An Instance only ever manages one and only one database (and that's true of
Parallel Server, too).
God only knows what the original poster was after, since I couldn't work out
what the hell was being talked about. If he wonders whether multiple
Instances on one box is possible, of course it is... you just need
sufficient RAM.
If he wonders whether multiple Databases can be on one box, of course it
is... you just need sufficient disk space (and a suitable directory
structure).
Can one Database be managed by two or more Instances? Yes -if you have
Parallel Server configured.
Can one Database be managed by one Instance and then (separately) by
another,differently-configured, Instance? -yes, provided you shut down the
first Instance, change the Oracle_sid and then startup specifying a
different init.ora.
Do Database structural changes require changes to the Instance? No. Add a
datafile, add a tablespace, move a datafile -the Instance is oblivious to
the change in the sense that that the Instance is configured by what's in
the init.ora, and none of those changes require re-configuration of the
init.ora.
So quite what "We want have two sid's: MY_SID1 and MY_SID2...When database
structure changes we make the modification to MY_SID1" means, I haven't a
clue. Frankly, it's meaningless.
Regards
HJR
>
> Anyway, you want two sets of datafiles, control-file etc.. so two physical
> different databases. Also two initSID.ora files to startup two different
> instances but you want to use one RDBMS.
> This is absolutely no problem.
>
> Reinier.
>
> <roni.hursti_at_laatukolmio.fi> wrote in message
> news:8smhpq$lkf$1_at_nnrp1.deja.com...
> > What I would like to have is:
> >
> > To have multible ORACLE_SID:s in one machine with one Oracle.
> >
> > Situation is something like this:
> >
> > We want have two sid's: MY_SID1 and MY_SID2
> >
> > When database structure changes we make the modification to MY_SID1.
> > At this time users use the MY_SID2.
> > After making the changes and tests to MY_SID1,
> > we notify the users to change sid to MY_SID1.
> >
> > When new database structure changes comes we make the changes to MY_SID2
> > ....
> >
> > In unix the change of sid (and thus database) should go like this:
> > $ export ORACLE_SID=MY_SID2
> > $ sqlplus system/manager @<<zz
> > desc my_table
> > zz
> > -->
> > Name Null? Type
> > ------------------------------- -------- ----
> > DUMMY VARCHAR2(1)
> >
> > $ export ORACLE_SID=MY_SID1
> > $ sqlplus system/manager @<<zz
> > desc my_table
> > zz
> > -->
> > Name Null? Type
> > ------------------------------- -------- ----
> > DUMMY NUMBER(1)
> >
> > Regards
> >
> > Roni
> >
> >
> > Sent via Deja.com http://www.deja.com/
> > Before you buy.
>
>
Received on Fri Oct 20 2000 - 11:00:00 CDT
