In this third article about
Oracle on Windows, we will take a look at the registry. Generally speaking, the
registry is a database that stores information about the setup and
configuration of a PC. If you are not a Windows administrator, and want to stay
in the Oracle world, so to speak, there are two excellent references you can
use to help demystify the Windows environment. One of them is free, and the
other is well worth the money. The free documentation is Oracle9i Database Getting Started
Release 2 (9.2) for Windows, and the other one is ORACLE9i for Windows 2000
Tips & Techniques, an Oracle Press book by Scott Jesse, Matthew Hart
and Michael Sale. Oracle’s documentation is pretty thorough, but if you want
even more detail about using Oracle on Windows, read the book.
Linux
and UNIX seem to get most of the press when it comes to discussing the
underlying operation system or platform, but as mentioned in previous articles,
Oracle’s presence on Windows is not uncommon anymore. If you consider Oracle’s
campaign to capture more of the small to medium business (SMB) market, (more so
with 10g and the idea of a “2 Day DBA”), chances are the SMBs are pure Windows
shops where UNIX is just thought of as that operating system managed by
introverts working in cold, dimly lit server rooms whose mortal enemies are
sunlight and any outdoor activity.
The registry
Keep
in mind two things about Oracle on Windows: it is easy to manage, and it is
just as easy to cause a significant problem with the OS. Why is that? The
answer is related to looking at both sides of a coin. On one side, you have
Microsoft and Oracle issuing strong advisories against manually editing the
registry, and on the other side, both of them tell you how to do just that.
There is no bottom line answer (to edit or not), so if you are not sure what
you are doing when it comes to editing the registry, but feel you must do so
without the requisite knowledge and skills, simply ask yourself if you feel
lucky today. Well, do you?
Actually, there is no need
for luck. And, there is no “try” involved either. “Try not. Do. Or do not. There
is no try” (okay, so I like using lines from movies to help make a point). You
can read 24 pages out of the Getting Started guide (Chapter 9) and be
sufficiently well-armed (or dangerous?) when it comes to working with the
registry. By knowing a handful of parameters, you can easily customize your
database (or instance, depending on the context of what you are trying to do)
and make it do things you cannot normally do via Oracle itself. Some of the
registry parameters have counterparts in UNIX, so it is useful to know what
can be done even if you do not know how it is done in UNIX.
Some useful registry parameters
SQLPATH
If you prefer to keep all of
your scripts in one place, or have multiple users on a PC (who may or may not
have set the “start in” property of a SQL*Plus desktop icon), you can use
SQLPATH to centrally manage and store your scripts. The default location is
ORACLE_HOME\dbs, and by specifying a different location, you can keep
extraneous files out of the software installation folders.
ORA_SID_AUTOSTART
This parameter is similar to
init.d rc scripts that start an instance as part of the boot process on UNIX.
In Windows, your instance may or may not be running, but if the service is not
running, the instance will not be running either. Upon a reboot or startup, you
can have your database (or databases) automatically start up (the service is
set to start automatically, which in turn enables the instance to be started,
which in turn means your database is open for business). With this parameter
set, you can also perform shutdown and startup simply by stopping and starting
the service (see the next parameter).
ORA_SID_SHUTDOWN
This goes hand in hand with
the autostart parameter because if set to true, the database is shutdown when
the service is stopped. Okay, shutdown how?
ORA_SID_SHUTDOWNTYPE
You can set one of three
values for this parameter: “a” for abort, “n” for normal, and “i” for immediate
(and is the default value).
ORA_SID_SHUTDOWN_TIMEOUT
To be on the safe side of
things, (i.e., ensure you have a clean shutdown if not using the abort option),
you can set a time (in seconds) for the service to wait before stopping.
Putting the parameters to practical use
Oracle’s documentation lists
many more parameters than what was just mentioned. I highlighted the
aforementioned parameters for a specific reason. Suppose you walk into a new
DBA job, to find that your recently departed/terminated predecessor did not
leave behind the passwords for sys or system. Users can still access the
database, but none of them has been granted the sysdba privilege. Not to worry.
Log in as an administrator and add yourself to the ORA_DBA group. You can
always re-create the password file, and by accessing the registry and services
control panel, you now have the ability to reset the passwords. In the
meantime, you can manage shutdowns and startups via the service.
It is easy to make a mistake and fix it
Before you start hacking
away at the registry, here is an exercise you can perform to help develop
skills and gain confidence in what you are doing. Take something innocuous in
the registry, such as your typed URLs, and export them. The exported file is a
“reg” file. Save it to your desktop or some other easy to find location. Delete
the TypedURLs folder (“key,” to be more precise) in the registry and start up
an Internet Explorer session. Note that your typed URL history in the address
list is gone. Exit the browser. Import your typed URLs and see how IE behaves.
If you are comfortable performing this exercise–and there is absolutely no
harm done if you make a mistake–then you will be sure of what you are doing
when performing a registry export of your Oracle entries. The “Typed URLs”
folder is found at HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TypedURLs.
After importing, if you see
the message shown below:
you are good to go.
In Closing
If you have been reluctant
to edit your registry because of the horror stories you have heard about how a
PC can be damaged (the technical term is “trashed”) due to an incorrect or
deleted registry parameter or value, then this article will have helped you
overcome some of that trepidation. The information in Chapter 9 of the Getting
Started guide clearly tells you how to edit the registry. There are times
and reasons why and when you should or can edit the registry, and there are
times when you should not (as a matter of routine). For example, if you want to
set an environment variable, later versions of Windows allow you to perform
this task via other means, so by all means, do it one of those ways. In Part 4
of this series, I’ll go into more detail about services.
