Friday, 10 December 2010

Flashback Explained


This is a very quick guide to Oracle Flashback.

Any form of restoring, such as Flashback, should always be done after reading the docs. for a final refresher - 10 minutes up-front may save hours later!

There are 2 basic types of flashback:
1. Flashback
2. Flashback Database

Plain "Flashback" is used to do one of these:
1. Perform queries that return past data
2. Perform queries that return metadata that shows a detailed history of changes to the database
3. Recover tables or rows to a previous point in time
4. Automatically track and archive transactional data changes
5. Roll back a transaction and its dependent transactions while the database remains online

"Flashback Database" is, in effect, a rewind button for the entire database. You simply tell Oracle how far back you want to go, and ta-da! it's done. It is a database-wide thing and can be thought of as an alternative to an RMAN restore/recovery, only faster, as no need to restore from tape, etc. It can be very useful recovering from unpleasant effects of patching, code releases, or anything that could screw the database. Flashback Database uses Flashback Logs & Archive Redo Logs, which are available to the database at all times. You need to decide how much space you allocate to flashback logs & archive redo logs, as disk can soon fill, if you aren't careful.

An example of Flashback Database:
The basic idea is to flashback the database to time T1, then ALTER OPEN DATABASE RESETLOGS, again, just like you do with an RMAN incomplete recovery, to have the database as it was at time T1. The database is now usable and ready for business - but everything that happened in the database since time T1 has now gone.
e.g. Assuming it is 16:30 on September 2nd. Someone did something insane in the database at 21:34 the day before (the 1st) utterly wrecking the database and the only sensible course of action left open is to flashback the database:
RMAN> FLASHBACK DATABASE TO TIME TO_DATE('01-SEP-2010 21:33:00','DD-MON-YYYY HH24:MI:SS')";

Note: As well as timestamp-based flashback, it can also be based on SCN or Restore Point. See the docs. for details. I recommend that you create a restore point before patching/upgrading, as it is then really easy to put the database back, should the patch/upgrade fail.
SCN-based flashback has a potential problem if the database has been flashed back or undergone PITR - again, search the docs. for "ambiguous scn".

If you want to check that the database data is what you want it to be - i.e. that you have flashed back to the right time - than issue:
RMAN> SQL 'ALTER DATABASE OPEN READ ONLY';

Assuming that you are happy with the database, you then do this:
RMAN> ALTER DATABASE OPEN RESETLOGS;

You don't have to do RESETLOGS, you can issue RECOVER, and the database fastforwards to the time you began the flashback - i.e. no data at all is lost, and you are back where you started. The docs. say that you could also export data before the RESETLOGS in order to get at "lost" data, but I recommend plain Flashback for that, as it is far less disruptive.

Plain "Flashback" refers to letting you view past states of database objects, or to return database objects to a previous state, without using point-in-time media recovery. This type of Flashback makes use of Undo, not Flashback Logs or Archive Redo Logs. Obviously, Undo configuration is key for this to work as expected, and you will have to work out how much disk space your undo file/s require, as well as enabling Automatic Undo Management, and reviewing such things as RETENTION GUARANTEE. Check out the docs.

As you can see, both types of flashback rely on disk space being available - you really do need to make sure that you provide enough disk space, and think through guaranteed retention, housekeeping any restore points, etc. to get what you want from flashback, and avoid problems

An example of plain Flashback:
An email arrives in the DBA mail queue. User XYZ has done it again and needs to "correct a small mishap", i.e. he has wrecked a table. It happened at 10:02 on December 3rd.
Assuming table name is USER01.TABLE01:
SQL> CREATE TABLE USER01.RESTORED_DATA AS
     (SELECT *
     FROM USER01.TABLE01
     AS OF TIMESTAMP
     TO_TIMESTAMP('03-DEC-2010 09:30:00', 'DD-MON-YYYY HH:MI:SS')
     );


User XYZ can now use the data, in table USER01.RESTORED_DATA,  to rectify his mistake.

Monday, 6 December 2010

DDL for Scheduler Jobs

DBMS_METADATA is great for getting any object DDL, but with scheduler jobs it's not so intuitive.
Rather than JOB, or whatever, it takes PROCOBJ:

Example:  
fakeuser@dev01>BEGIN
  2  DBMS_SCHEDULER.create_job (
  3  job_name        => 'my_fake_job',
  4  job_type        => 'PLSQL_BLOCK',
  5  job_action      => 'BEGIN DBMS_STATS.gather_schema_stats(''SCOTT''); END;',
  6  start_date      => SYSTIMESTAMP,
  7  repeat_interval => 'freq=hourly; byminute=0',
  8  end_date        => NULL,
  9  enabled         => TRUE,
 10  comments        => 'My fake job.');
 11  end;
 12  /

PL/SQL procedure successfully completed.

fakeuser@dev01>select dbms_metadata.get_ddl('PROCOBJ',JOB_NAME) FROM USER_SCHEDULER_JOBS;

DBMS_METADATA.GET_DDL('PROCOBJ',JOB_NAME)
--------------------------------------------------------------------------------


BEGIN
dbms_scheduler.create_job('"MY_FAKE_JOB"',
job_type=>'PLSQL_BLOCK', job_action=>
'BEGIN DBMS_STATS.gather_schema_stats(''SCOTT''); END;'
, number_of_arguments=>0,
start_date=>TO_TIMESTAMP_TZ('06-DEC-2010 01.26.37.186707000 PM +00:00','DD-MON-R
RRR HH.MI.SSXFF AM TZR','NLS_DATE_LANGUAGE=english'), repeat_interval=>
'freq=hourly; byminute=0'
, end_date=>NULL,
job_class=>'"DEFAULT_JOB_CLASS"', enabled=>FALSE, auto_drop=>TRUE,comments=>
'My fake job.'
);
dbms_scheduler.enable('"MY_FAKE_JOB"');
COMMIT;
END;

Monday, 29 November 2010

Kill a RACGIMON Process

You may see that a racgimon process is consuming ever-increasing CPU.

It is just a matter of killing the operating system process.

It is safe and supported to kill a runaway racgimon process, as it will respawn.

Be patient! It WILL respawn, but can take 10 minutes, or so, though usually just a couple of minutes.

Clone A User

I use this script often and think it's brilliant.


Rem
Rem $Header: crusrlk.sql 03-apr-2007 $
Rem
Rem Author: raymond.wauben@gmail.com
Rem    NAME
Rem      crusrlk.sql
Rem    DESCRIPTION
Rem      Create a new database schema/user like an existing database schema/user.
Rem    RETURNS
Rem
Rem    NOTES
Rem      This script must be run while connected as a user with DBA privileges.
Rem      In case of directory users, new users reside in the same directory
Rem      information tree as existing users and database account equals to
Rem      directory account.
Rem      This script does not completely clone user SYS.
Rem      This script has been tested successfully against the following
Rem      Oracle Server version(s):
Rem        - Oracle Server 10g Release 1;
Rem        - Oracle Server 10g Release 2.
Rem    MODIFIED   (MM/DD/YY)
Rem     rwauben    04/03/07 - Creation


set define '%'
set echo off
set feedback off
set heading off
set linesize 160
set pagesize 0
set pause on
set trimspool on
set verify off


clear screen


prompt --------------------------------------------------------------------------------;
prompt Create a new schema/user like an existing schema/user.;
prompt Defaults are shown between brackets [].;
prompt --------------------------------------------------------------------------------;


accept OriginalUser prompt "Enter existing database schema/user [%_USER]: " default %_USER
accept NewUser      prompt "Enter new database schema/user [SCOTT]: " default SCOTT
accept NewPassword  prompt "Enter password for new database schema/user (Leave blank to copy): " hide


prompt ================================================================================;
prompt You entered the following information:
prompt ;


prompt Existing database schema/user     : %OriginalUser
prompt New database schema/user          : "%NewUser"


prompt ;
prompt If this is correct, press ENTER to generate SQL and PL/SQL statements and
prompt create the new schema/user, otherwise press CTRL+C to cancel and return to the
prompt SQL*Plus prompt.;
prompt ;
prompt ================================================================================;
pause


undefine v_file_name
column v_file_name new_value v_file_name


undefine v_remove_command
column v_remove_command new_value v_remove_command


set termout off


select to_char(sysdate,'YYYY-MON-DD_HH24-MI-SS') || '_' || user || '.sql' as v_file_name from dual;


Rem Determine use of either Windows 'del' command or Linux/Unix 'rm' command.
select case when lower(program) like '%.exe' then 'del'
       else 'rm'
       end as v_remove_command
from v$session
where sid = (select distinct sid
from v$mystat);


set termout on


--spool %v_file_name




Rem Build CREATE USER statement. --------------------------------------------------


select 'CREATE USER "%NewUser" ' ||
       case when password = 'EXTERNAL' then 'IDENTIFIED EXTERNALLY'
            when password = 'GLOBAL'   then 'IDENTIFIED GLOBALLY AS ''' ||
              replace (external_name,'%OriginalUser','"%NewUser"') || ''''
            else 'IDENTIFIED BY ' ||
              decode(upper('%NewPassword'),null,'VALUES ''' || password || '''','%NewPassword')
       end
       || ' DEFAULT TABLESPACE "' || default_tablespace ||
       '" TEMPORARY TABLESPACE "' || temporary_tablespace ||
       '" PROFILE ' || profile || ' ACCOUNT ' ||
       decode(account_status,'OPEN','UNLOCK',
                             'EXPIRED','UNLOCK PASSWORD EXPIRE',
                             'EXPIRED(GRACE)','UNLOCK',
                             'LOCKED(TIMED)','UNLOCK',
                             'LOCKED','LOCK',
                             'EXPIRED & LOCKED(TIMED)','UNLOCK PASSWORD EXPIRE',
                             'EXPIRED(GRACE) & LOCKED(TIMED)','UNLOCK',
                             'EXPIRED & LOCKED','LOCK PASSWORD EXPIRE',
                             'EXPIRED(GRACE) & LOCKED','LOCK',
                             'LOCK') || ';'
from dba_users
where username = upper('%OriginalUser');


Rem -------------------------------------------------------------------------------




Rem Check tablespace quotas and build ALTER USER statements. ----------------------


select 'ALTER USER "%NewUser" QUOTA ' ||
       decode(max_bytes,-1,'UNLIMITED',max_bytes) ||
       ' ON "' || tablespace_name || '";'
from sys.dba_ts_quotas
where username = upper('%OriginalUser');


Rem -------------------------------------------------------------------------------




Rem Check SYSDBA and/or SYSOPER privileges and build GRANT statement. -------------


select decode(sysdba, 'TRUE', 'GRANT SYSDBA TO "%NewUser";', null) sysdba
from v$pwfile_users
where username = upper('%OriginalUser');


select decode(sysoper, 'TRUE', 'GRANT SYSOPER TO "%NewUser";', null) sysoper
from v$pwfile_users
where username = upper('%OriginalUser');


Rem -------------------------------------------------------------------------------




Rem Check system privileges and build GRANT statements. ---------------------------


select 'GRANT ' || privilege || ' TO "%NewUser"' ||
       decode(admin_option,'YES',' WITH ADMIN OPTION;',';')
from sys.dba_sys_privs
where grantee = upper('%OriginalUser');


Rem -------------------------------------------------------------------------------




Rem Check roles and build GRANT statements. ---------------------------------------


select 'GRANT ' || granted_role || ' TO "%NewUser"' ||
       decode(admin_option,'YES',' WITH ADMIN OPTION;',';')
from sys.dba_role_privs
where grantee = upper('%OriginalUser');


Rem -------------------------------------------------------------------------------




Rem Check default roles and build ALTER USER ... DEFAULT ROLE ... statement. ------


set serveroutput on


declare
  v_default_roles varchar2(4000) := null;
begin
  for c1 in (select * from sys.dba_role_privs
             where grantee = upper('%OriginalUser')
             and default_role = 'YES')
  loop
    if length(v_default_roles) > 0 then
      v_default_roles := v_default_roles || ',' || c1.granted_role;
    else
      v_default_roles := v_default_roles || c1.granted_role;
    end if;
  end loop;


  if length(v_default_roles) > 0 then
    dbms_output.put_line('ALTER USER "%NewUser" DEFAULT ROLE ' || v_default_roles || ';');
  end if;
end;
/


set serveroutput off


Rem -------------------------------------------------------------------------------




Rem Check table and column privileges and build GRANT statements. -----------------


select 'GRANT ' || privilege || ' ON ' || owner || '."' || table_name ||
       '" TO "%NewUser"' || decode(grantable,'YES',' WITH GRANT OPTION;',';')
from (select usrge.name grantee, usr.name owner, obj.name table_name, null column_name,
      usrgr.name grantor, tabprivmap.name privilege,
      decode(mod(objauth.option$,2), 1, 'YES', 'NO') grantable,
      decode(bitand(objauth.option$,2), 2, 'YES', 'NO') hierarchy,
      decode(obj.type#, 2, 'TABLE', 4, 'VIEW', 6, 'SEQUENCE', 7, 'PROCEDURE',
                        8, 'FUNCTION', 9, 'PACKAGE', 13, 'TYPE', 22, 'LIBRARY',
                        23, 'DIRECTORY', 24, 'QUEUE', 28, 'JAVA SOURCE',
                        29, 'JAVA CLASS', 30, 'JAVA RESOURCE', 32, 'INDEXTYPE',
                        33, 'OPERATOR', 42, 'MATERIALIZED VIEW',
                        'UNDEFINED') object_type
from sys.objauth$ objauth, sys.obj$ obj, sys.user$ usr, sys.user$ usrgr, sys.user$ usrge,
     sys.table_privilege_map tabprivmap
where objauth.obj# = obj.obj#
and objauth.grantor# = usrgr.user#
and objauth.grantee# = usrge.user#
and objauth.col# is null
and objauth.privilege# = tabprivmap.privilege
and usr.user# = obj.owner#
and obj.type# in (2, 4, 6, 7, 8, 9, 13, 22, 24, 28, 29, 30, 32, 33, 42)
and usrge.name = upper('%OriginalUser')
union all
select usrge.name, usr.name, obj.name, col.name, usrgr.name, tabprivmap.name,
       decode(mod(objauth.option$,2), 1, 'YES', 'NO'),
       null hierarhy,
       decode(obj.type#, 2, 'TABLE', 4, 'VIEW', 42, 'MATERIALIZED VIEW')
from sys.objauth$ objauth, sys.obj$ obj, sys.user$ usr, sys.user$ usrgr, sys.user$ usrge,
     sys.col$ col, sys.table_privilege_map tabprivmap
where objauth.obj# = obj.obj#
and objauth.grantor# = usrgr.user#
and objauth.grantee# = usrge.user#
and objauth.obj# = col.obj#
and objauth.col# = col.col#
and objauth.col# is not null
and objauth.privilege# = tabprivmap.privilege
and usr.user# = obj.owner#
and obj.type# in (2, 4, 42)
and bitand(col.property, 32) = 0
and usrge.name = upper('%OriginalUser'));


Rem -------------------------------------------------------------------------------




Rem Check Java privileges and build PL/SQL statements. ----------------------------


set serveroutput on


declare
  i integer := 1;
begin
  for c1 in (select kind, grantee, type_schema, type_name,
             name, action, enabled, seq
             from sys.dba_java_policy
             where grantee = upper('%OriginalUser')
             order by seq)
  loop
    if i = 1 then
      dbms_output.put_line('DECLARE');
      dbms_output.put_line('KEYNUM NUMBER;');
      dbms_output.put_line('BEGIN');
      i := 2;
    end if;


    if c1.kind = 'GRANT' then
      dbms_output.put_line('SYS.DBMS_JAVA.GRANT_PERMISSION(GRANTEE => ''' ||
                                  upper('"%NewUser"') || ''', PERMISSION_TYPE => ''' ||
                                  c1.type_schema || ':' || c1.type_name ||
                                  ''', PERMISSION_NAME => ''' || c1.name ||
                                  ''', PERMISSION_ACTION => ''' || c1.action ||
                                  ''', KEY => KEYNUM);');
    elsif c1.kind = 'RESTRICT' then
      dbms_output.put_line('SYS.DBMS_JAVA.RESTRICT_PERMISSION(GRANTEE => ''' ||
                                  upper('"%NewUser"') || ''', PERMISSION_TYPE => ''' ||
                                  c1.type_schema || ':' || c1.type_name ||
                                  ''', PERMISSION_NAME => ''' || c1.name ||
                                  ''', PERMISSION_ACTION => ''' || c1.action ||
                                  ''', KEY => KEYNUM);');
    end if;
  end loop;


  if i = 2 then
    dbms_output.put_line('END;');
    dbms_output.put_line('/');
  end if;
end;
/


set serveroutput off


Rem -------------------------------------------------------------------------------




Rem Check resource group privileges and build PL/SQL statements. ------------------


set serveroutput on


declare
  i integer := 1;
  v_initial_group varchar2(30) := null;
begin
  for c1 in (select grantee,
                    granted_group,
                    decode(grant_option,'YES','TRUE','FALSE') grant_option,
                    initial_group
             from dba_rsrc_consumer_group_privs
             where grantee = upper('%OriginalUser'))
  loop
    if i = 1 then
      dbms_output.put_line('BEGIN');
      dbms_output.put_line('SYS.DBMS_RESOURCE_MANAGER.CLEAR_PENDING_AREA();');
      dbms_output.put_line('SYS.DBMS_RESOURCE_MANAGER.CREATE_PENDING_AREA();');
      i := 2;
    end if;


    dbms_output.put_line('SYS.DBMS_RESOURCE_MANAGER_PRIVS.GRANT_SWITCH_CONSUMER_GROUP(''"%NewUser"'',''' || c1.granted_group || ''',' || c1.grant_option || ');');


    if c1.initial_group = 'YES' then
      v_initial_group := c1.granted_group;
    end if;
  end loop;


  if i = 2 then
    dbms_output.put_line('SYS.DBMS_RESOURCE_MANAGER.SUBMIT_PENDING_AREA();');
    dbms_output.put_line('END;');
    dbms_output.put_line('/');
  end if;


  if v_initial_group is not null then
    dbms_output.put_line('BEGIN');
    dbms_output.put_line('SYS.DBMS_RESOURCE_MANAGER.SET_INITIAL_CONSUMER_GROUP(''"%NewUser"'',''' || v_initial_group || ''');');
    dbms_output.put_line('END;');
    dbms_output.put_line('/');
  end if;
end;
/


set serveroutput off


Rem -------------------------------------------------------------------------------




Rem Check proxy authentication and build ALTER USER ... statements. ---------------


set serveroutput on


declare
  v_proxy_roles varchar2(4000);
begin
  for c1 in (select distinct decode(proxy,null,'ENTERPRISE USERS',proxy) proxy,
                    client,
                    decode(authentication,'YES',' AUTHENTICATION REQUIRED') authentication
             from sys.dba_proxies
             where client = upper('%OriginalUser'))
  loop
    v_proxy_roles := null;


    for c2 in (select role
             from sys.dba_proxies
             where nvl(proxy,'ENTERPRISE USERS') = c1.proxy
             and client = c1.client
             and role is not null)
    loop
      if v_proxy_roles is null then
        v_proxy_roles := ' WITH ROLES ' || c2.role;
      else
        v_proxy_roles := v_proxy_roles || ', ' || c2.role;
      end if;
    end loop;


    dbms_output.put_line('ALTER USER "%NewUser" GRANT CONNECT THROUGH ' || c1.proxy || v_proxy_roles || c1.authentication || ';');
  end loop;
end;
/


set serveroutput off


Rem -------------------------------------------------------------------------------
Prompt ;
Prompt ;
prompt --------------------------------------------------------------------------------;
prompt --------------------------   C O M P L E T E D   -------------------------------;
prompt --------------------------------------------------------------------------------;

Data Pump With Timestamp

Old export had CONSISTENT=Y, but Data Dump does not. Instead, you use the following syntax:


nice -n 19 expdp system schemas=scott directory=TEST_DIR dumpfile=scott.dmp logfile=scott.log job_name=scott_job flashback_time=\"TO_TIMESTAMP\(sysdate, \'DD-MM-YYYY HH24:MI:SS\'\)\"