Neil Chandler's DBA Blog

A resource for Database Professionals

Posts Tagged ‘oracle

Releasing to schemas the easy way

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Sometimes we occasionally just miss the obvious, for years. Just noticed that an easy way to release code to a particular schema is to login as your normal DBA user (USER1) [as preferred by audit], use the alter session command to switch to point to the release schema (USER2) and run your DDL. Oracle behaves, from an object-owner perspective, as if you are logged-in as the schema owner without all the negative aspects of actually having to login as the schema owner or prefix all object with the schema owner.

This is particularly useful when you have multiple schemas within the database and you are releasing to more than one schema at once.



sqlplus USER1@ORCL

SQL*Plus: Release Production on Wed Sep 17 12:17:36 2014

Copyright (c) 1982, 2010, Oracle. All rights reserved.

Enter password:

Connected to:
Oracle Database 11g Enterprise Edition Release - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

12:17:38 USER1@ORCL>select owner,table_name from dba_tables where table_name = 'N1';

no rows selected

12:17:46 USER1@ORCL>create table n1 (c1 date);

Table created.

12:17:56 USER1@ORCL>select owner,table_name from dba_tables where table_name = 'N1';

OWNER                          TABLE_NAME
------------------------------ ------------------------------
USER1                          N1

12:17:57 USER1@ORCL>alter session set current_schema=USER2;

Session altered.

12:18:08 USER1@ORCL>create table n1 (c1 date);

Table created.

12:18:11 USER1@ORCL>select owner,table_name from dba_tables where table_name = 'N1';

OWNER                          TABLE_NAME
------------------------------ ------------------------------
USER2                          N1
USER1                          N1



Written by Neil Chandler

28th September 2014 at 22:46

Posted in Administration, audit, SCHEMA

Tagged with , , ,

SCAN listener logs – where are they?

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These are a bit of a pain as their location isn’t intuitive. So to remind me where they are:

Login to the server(s) as the grid owner and check the scan listener status. This will show you the location of the listener log. cd to just below the diag directory and you’re off!:

server-name:/u01/grid>ps -ef | grep SCAN
 grid 8542 8282 0 10:20 pts/0 00:00:00 grep SCAN
 grid 9349 1 0 Mar07 ? 00:07:33 /u01/app/11g/grid/bin/tnslsnr LISTENER_SCAN1 -inherit

server-name:/u01/grid>lsnrctl status LISTENER_SCAN1
LSNRCTL for Linux: Version - Production on 28-MAY-2014 10:20:12
Copyright (c) 1991, 2013, Oracle. All rights reserved.
 Version TNSLSNR for Linux: Version - Production
 Start Date 07-MAR-2014 17:27:50
 Uptime 81 days 15 hr. 52 min. 21 sec
 Trace Level off
 Security ON: Local OS Authentication
 Listener Parameter File /u01/app/11g/grid/network/admin/listener.ora
 Listener Log File /u01/app/11g/grid/log/diag/tnslsnr/server-name/listener_scan1/alert/log.xml
 Listening Endpoints Summary...
 Services Summary...
 Service "FRONT_APP_DB_SVC.WORLD" has 2 instance(s).
 Instance "ORCL1", status READY, has 1 handler(s) for this service...
 Instance "ORCL2", status READY, has 1 handler(s) for this service...
 Service "ORCL.WORLD" has 2 instance(s).
 Instance "ORCL1", status READY, has 1 handler(s) for this service...
 Instance "ORCL2", status READY, has 1 handler(s) for this service...
 Service "ORCLXDB.WORLD" has 2 instance(s).
 Instance "ORCL1", status READY, has 1 handler(s) for this service...
 Instance "ORCL2", status READY, has 1 handler(s) for this service...
 The command completed successfully

server-name:/u01/app/11g/grid/log>cd /u01/app/11g/grid/log
ADRCI: Release - Production on Wed May 28 10:22:47 2014
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
ADR base = "/u01/app/11g/grid/log"
 adrci> show homes
 ADR Homes:
adrci> show alert
Choose the alert log from the following homes to view:
1: diag/asmcmd/user_grid/server-name
 2: diag/tnslsnr/server-name/listener_scan3
 3: diag/tnslsnr/server-name/listener_scan2
 4: diag/tnslsnr/server-name/listener_scan1
 5: diag/asmtool/user_root/host_3797755080_80
 Q: to quit
Please select option: 4

and there we are…
remember to be on the correct host for each scan,
otherwise the alert (listener) log file will be out of date.


Written by Neil Chandler

6th June 2014 at 06:28

Posted in Problem Solving, RAC

Tagged with , , ,

Developers Killing Sessions

with 3 comments

When you end up spending a far great a percentage of your day than seems sensible killing off Java connections that Developers have carelessly left lying around, locking objects all over the place, you need a solution to get them to go away. The solution is to let them do it themselves!

I’m not advocating granting ALTER SYSTEM to Developers! That way madness lies, or certainly some unintended consequences. I’m all for Dev’s having a lot of freedom in the database, just not freedom with the database.

So, creating a stored procedure (in this example as sys, but as any user with an explicit ALTER SYSTEM privilege granted will do) to kill sessions without allowing too much latitude to do anything else seems appropriate. Here’s one I built earlier:


create or replace procedure sys.kill_session 
 ( p_sid IN number, p_serial IN number, p_instance IN number) as
 -- Neil Chandler. Grant the ability to kill session on a restricted basis. 21.07.2010
 l_username varchar2(30) := null;
 l_priv number := 1;
 -- Who owns the session?
 select username into l_username
 from gv$session
 where sid = p_sid and serial#=p_serial and inst_id = p_instance;
 -- Check for DBA role
 select count(*) into l_priv
 from dba_role_privs
 where grantee = l_username and granted_role = 'DBA';
 -- If the user has the DBA priv, deny the kill request
 if l_priv > 0 or l_username is null
  ('User request to kill session '||p_sid||','||p_serial||',@'||p_instance||
   ' denied. Session is for privileged user '||l_username||'.');
   ('Killing user '||l_username||' - '||p_sid||','||p_serial||',@'||p_instance);
 execute immediate 'alter system disconnect session '''||
                   ''' immediate';
 end if;

-- and let the proc be seen and used
create or replace public synonym kill_session for sys.kill_session; 
grant execute on kill_session to (whomever);

Then a nifty bit of sql to generate the kill commands for the Developers. 
Please include your favourite columns from gv$session:

select username,status,blocking_session,
 'exec kill_session ('|| sid||','||serial#||','||inst_id||')' Kill_Command 
 from gv$session
where username is not null
  and type <> 'BACKGROUND'

--------- ------- ---------------- ------------------------------------ 
SYS       ACTIVE                   exec kill_session (31,65,1)
SYSTEM    INACTIVE                 exec kill_session (58,207,1)
USER_1    INACTIVE                 exec kill_session (59,404,1)
USER_2    INACTIVE                 exec kill_session (72,138,1)
USER_2    INACTIVE                 exec kill_session (46,99,2)

May the odds be forever in your favour. Let the killing commence…

Written by Neil Chandler

29th May 2014 at 11:13

The trouble with Timezones & Grid Infrastructure

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When installing Oracle Grid Infrastructure 11.2 (and all other releases), you need to make sure that you have all of the server setting correct and to standard before you do the install. One that bit me recently was the timezone setting. The Red Hat 6.4 server(s) in question has the correct file in /etc/localtime (copied from /usr/share/zoneinfo/whatever). If I type in date, I get the reply in the correct timezone (GMT/BST as I’m in London), so all seems correct.

However, the slack Unix Sysadmin (which might or might not have been me) had not put the correct setting in /etc/sysconfig/clock. Unfortunately, when you install Grid Infrastructure, the setting is read from /etc/sysconfig/clock and embedded into a Grid Inforastructure config file. $GRID_HOME/crs/install/s_crsconfig_hostname_env.txt

### This file can be used to modify the NLS_LANG environment variable, which determines the charset to be used for messages.

### For example, a new charset can be configured by setting NLS_LANG=JAPANESE_JAPAN.UTF8

### Do not modify this file except to change NLS_LANG, or under the direction of Oracle Support Services





If you change this entry, and you should check with Oracle Support if this is OK for your site, and you will need to restart Grid Infrastructure. The one thing about this that I really don’t like is that Oracle is storing a runtime configuration file in a an install directory. Does it do that anywhere else?

Written by Neil Chandler

11th April 2014 at 10:51

Online index problem – ORA-08104

with 3 comments

So, you’re creating (or rebuilding) an index ONLINE on a busy system. Your session dies, or it becomes necessary to kill the command, you may find that Oracle does not (always manage to) automatically clean up after itself.

CREATE INDEX my_ind ON my_table (mycol ASC)

ORA-01013: user requested cancel of current operation

select * from user_indexes where index_name = 'my_ind';

my_ind     NORMAL

OMG! WTF! TLA’s! The index is there, even though I cancelled the create statement! Lets drop it…

drop index my_ind;
 ERROR at line 1:
 ORA-08104: this index object <B>79722</B> is being online built or rebuilt

So, HOW do I sort out this mess? Use DBMS_REPAIR!

  1  declare
  2  lv_ret BOOLEAN;
  3  begin
  4  lv_ret := dbms_repair.online_index_clean(79722);
  5* end;

select * from user_indexes where index_name = 'ind_name';

no rows selected

Bang! and the index (or, rather, left-over temporary extents from the build attempt) is gone, ready for you to try again.

Written by Neil Chandler

12th March 2014 at 23:57

SQL Plan Management – 12C dumb feature

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In Oracle 11G, Oracle introduced SQL Plan Management (SPM). It is excellent (I love it to bits). It allows you to create Baselines against SQL which lock-down the SQL execution plan. No more plan flips. More consistency. Perfect.

Whenever some Baselined SQL is ran, Oracle still parses it and compares the parsed output to the accepted (Evolved) baselines. If the newly parsed plan is better, a new baseline is added to DBA_SQL_PLAN_BASELINES but is NOT accepted. This means that you need to spend time manually accepting the baseline; running the command DBMS_SPM.EVOLVE_SQL_BASELINE plan and checking the new plan. IF you want it, and/or Oracle evaluates that is it a better plan for that particular set of bind variables, the plan is accepted and becomes a candidate to be used by future execution of your SQL. Complete control over your execution plans.

So, Oracle, what’s all this about in Oracle 12C, eh?

In Oracle 12C there’s a new SPM Evolve advisor task. “By default, SYS_AUTO_SPM_EVOLVE_TASK runs daily in the scheduled maintenance window” – So, it runs every night and by default it runs DBMS_SPM.EVOLVE_SQL_BASELINE for all new baselines created today and automatically accepts the new plans.

BY DEFAULT? NO! the Oracle, NO!

That is precisely what I don’t want from baselines – Oracle making it’s own mind up about plans without any input from me. I’m using baselines to stop Oracle changing its mind. To explicitly limit the number of paths allowed by the Optimizer to ones I know about and with which I am comfortable. Don’t introduce functionality to do the opposite.

So, immediately following the installation of 12C, I would recommend running (you need to be SYS for this):

           (PARAMETER_NAME = 'TIME_LIMIT') ) );

------------------------- ----------
ACCEPT_PLANS              TRUE
TIME_LIMIT                3600

Then run:

    'ACCEPT_PLANS', 'false');

OK, back where we were, with any baselines fixed in place and doing what I want them to do! Not change.

Written by Neil Chandler

8th December 2013 at 09:57

UKOUG Tech13

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I attended the UKOUG Tech13 conference this week, along with over 1,000 other Oracle Technical Professionals (and some less-professional too), to learn what I could about how everyone else is doing stuff with Oracle, and how it works. And to share some experiences.

I wasn’t disappointed.

As with everything these days, there was a lot of activity on Twitter about the 4 day conference, and one of the sponsors, RittmanMead, had knocked up a rather wonderful tweet visualisation (click here to see how – magical):


As you can see, there are some of the worlds best-known Oracle techies on the list of top speaker tweets, but I am as pleased as anything to have been in the top 10 most tweeted speakers at the end of the 1st day (although I suspect that’s because I knew where the pub was, rather than too much about my 1st presentation)

Get involved with the Oracle community, in whatever form. It leads to professional and personal development, real insights about what Oracle really does (rather than what the marketeers say), and some good friendships. And possibly liver disease judging by the amount of alcohol consumed by all. :-)


Written by Neil Chandler

7th December 2013 at 10:03

Posted in Management, UKOUG

Tagged with , , ,


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