Java Backup
A good backup is always a DBA's best friend, especially when the database has a large number of Java Classes, Java Resources, Java Grants and Policies. No special tool is provided by Oracle to handle the Java objects backup, you'll need to use standard utilities.
A Java Classes Backup is made by a full database export without rows.
Example of a full database export:
% exp userid=system full=y ROWS=N file=full_export_norows.dmp
To restore Java Classes from previously taken backup:
% imp userid=system INGORE=Y full=y
Java Privileges Backup is simply a Java grants and policies extraction from the database. Here is the script to extract the Java information (Oracle Metalink, DocID: 183825):
spool setjvmprivs.sql
set echo off
set feedback off
set heading off
set linesize 80
set pagesize 1000
column stmt format a70 word_wrapped
select 'exec '||stmt
from (select seq, 'dbms_java.grant_permission('''||grantee||''','''||
type_schema||':'||type_name||''','''||name||''','''||action||
''');' stmt
from dba_java_policy
where grantee not in ('JAVADEBUGPRIV', 'JAVASYSPRIV', 'JAVAUSERPRIV',
'JAVA_ADMIN', 'JAVA_DEPLOY', 'SYS', 'PUBLIC') and
type_name!='oracle.aurora.rdbms.security.PolicyTablePermission'
union all
select seq,'dbms_java.grant_policy_permission('''||a.grantee||''','''||
u.name||''','''||permition||''','''||action||''');' stmt
from sys.user$ u,
(select seq, grantee,
to_number(substr(name,1,instr(name,':')-1)) userid,
substr(name,instr(name,':')+1,instr(name,'#') -
instr(name,':')-1) permition,
substr(name,instr(name,'#')+1 ) action
from dba_java_policy
where grantee not in ('JAVADEBUGPRIV', 'JAVASYSPRIV',
'JAVAUSERPRIV', 'JAVA_ADMIN', 'JAVA_DEPLOY',
'SYS', 'PUBLIC') and
type_name =
'oracle.aurora.rdbms.security.PolicyTablePermission') a
where u.user#=userid) order by seq;
column stmt clear
set pagesize 24
set heading on
spool off
Output from that script should produce Java recreation commands like:
exec dbms_java.grant_permission('SCOTT','SYS:java.io.FilePermission','temp\output.txt','read,write);
Conclusion
Recent surveys showed interesting answers to the question of 'why use Java'.
Some said because Java developers are easier to find than other developers, others are of the opinion that the development time is reduced due to Java code's simplicity and accessibility. Most of them believe that Java's performance will be comparable to other natively compiled languages in the future.
Once loaded, the Java option will need attention from a DBA.
When it is no longer needed, it should be removed, rather than just sizing down the Java pool.
