MacManitou's Blog

When importing a backup you might have run into the problem that the ampersands (&) or colon () characters are used as bind variables in PL/SQL. This is actually no real problem, as you can simply change the substitution character using the DEFINE setting in SQL*Plus:
<pre class=“brush: sql”>SET DEFINE ~</pre>
The usual substitution mechanism an ampersands would trigger, is now suppressed.

Other methods:
Define an escape character:
<pre class=“brush: sql”>
SET ESCAPE ‘\’
SELECT ‘\&abc’ FROM dual;
</pre>
Don’t scan for substitution variables:
<pre class=“brush: sql”>
SET SCAN OFF
SELECT ‘&ABC’ x FROM dual;
</pre>
Another way to escape the & would be to use concatenation, which would not require any SET commands -
<pre class=“brush: sql”>
SELECT ‘Laurel ‘ || ‘&’ || ‘ Hardy’ FROM dual;
</pre>
Use the 10g Quoting mechanism:
<pre class=“brush: sql”>
Syntax
q’[QUOTE_CHAR]Text[QUOTE_CHAR]‘
Make sure that the QUOTE_CHAR followed by an ‘ doesn’t exist in the text.
SELECT q’{This is Orafaq’s ‘quoted’ text field}’ FROM DUAL;
</pre>

You can also turn off substitutions by setting define to off:

<pre class=“brush: sql”>
SET DEFINE OFF
</pre>

When you need it, just turn it on again:

<pre class=“brush: sql”>
SET DEFINE ON
</pre>

Reference:

http://kwatog.com/blog/oracle/enable-disable-bind-variable-in-sqlplus/

Sometimes it is unnecessary to use ArchiveLog mode with the Oracle database. If you do not know what ArchiveLog Mode is – here is a short statement:

“Any Oracle database that contains important data should be running in ARCHIVELOG mode. Running in Archive log mode enables you to take hot backups and perform point-in-time recovery.”
So if you do not want this feature you can disable it following these steps:

        - Login to your server as oracle user
        - start sqlplus as sysdba
                sqlplus “/ as sysdba”
        - run the following commands
                shutdown abort
                startup mount
                alter database noarchivelog;
                alter database open;
        - to test if you where successful just run the query:
                select name, log_mode from v$database;

Remember that once you disable archive log mode you need to take a fresh backup once archive log mode is turned back on.
Be aware that if a disk failure occurs while in NOARCHIVELOG mode, you can only restore the database to the point of the most recent full database backup.
To switch back from archivelog to noarchivelog mode, just repeat the relevant steps above specifying: ALTER DATABASE NOARCHIVELOG;

For RAC environments, read the following link:

http://www.dba-oracle.com/bk_disable_archive_log_mode.htm