Here’s a quirky little bug that appeared on the OTN database forum in the last 24 hours which (in 12c, at least) produces an issue which I can best demonstrate with the following cut-n-paste:
SQL> desc purple
Name Null? Type
----------------------------------- -------- ------------------------
G_COLUMN_001 NOT NULL NUMBER(9)
SQL> select p.*
2 from GREEN g
3 join RED r on g.G_COLUMN_001 = r.G_COLUMN_001
4 join PURPLE p on g.G_COLUMN_001 = p. (more...)
There was a little conversation on Oracle-L about ASH (active session history) recently which I thought worth highlighting – partly because it raised a detail that I had got wrong until Tim Gorman corrected me a few years ago.
Once every second the dynamic performance view v$active_session_history copies information about active sessions from v$session. (There are a couple of exceptions to the this rule – for example if a session has called dbms_lock.sleep() it will appear (more...)
I logged into an Oracle 12.1 database and ran the ALTER DATABASE BEGIN BACKUP command. This told Oracle I was about to start a hot backup:
C:UsersAdministrator>sqlplus / as sysdba
SQL*Plus: Release 188.8.131.52.0 Production on Thu Mar 26 10:08:51 2015
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Oracle Database 12c Enterprise Edition Release 184.108.40.206.0 - 64bit Production
In a few weeks I’ll be talking about monitoring Oracle GoldenGolden using Oracle Enterprise Manager 12c at IOUG Collaborate in Las Vegas. This is one of the few presentations I will be giving that week (going to be a busy week). Although this posting, kinda mirrors a previous post on how to configure the Oracle GoldenGate JAgent, it is relevant because:
1. Oracle changed the name of the JAgent to Oracle Monitor Agent
2. Steps (more...)
This post has nothing to do with Oracle or Enterprise Manager at all, so if that’s all you’re interested in you can stop reading now.
Yesterday I ran into the situation where PowerPoint would only open minimized on the task bar and nothing I could do would get it to budge from there. The only way I could get PowerPoint to start and be displayed on any monitor was to start it in safe mode. (more...)
Mary Ann Davidson wrote a great piece on her security blog today, which basically talked about focusing on the important vulnerabilities, not necessarily the ones that get the most press. Added to that, the risk associated with a vulnerability may well be different for you compared to everyone else, depending on how your system is used. I agree with what she is saying, but I’m going to take a slightly different angle on the subject.
<<…Overview of what the Tech15 volunteers don't do
When you go to a conference like UKOUG Tech15 there are hundreds of talks given over several days and a dozen or so streams. Who decides what is presented and how do they decide?
You do. Well, I’d say you have about 60-70% of the input, if you are a member of the UKOUG (and I know many reading this are not – but you are probably (more...)
Some time ago I wrote a blog note describing a hack for refreshing a large materialized view with minimum overhead by taking advantage of a single-partition partitioned table. This note describes how Oracle 12c now gives you an official way of doing something similar – the “out of place” refresh.
I’ll start by creating a matieralized view and creating a couple of indexes on the resulting underlying table; then show you three different calls to refresh (more...)
I’ve just found out I’ve got a paper selected for the UKOUG System Event on May 20th. Check out my badge.
I was a spectator at last year’s event. At first glance you might think much of the content is not directly related to my job, since I’m not a system administrator, virtual infrastructure administrator and I don’t use any Oracle engineered systems, appliances or storage products. Having said all that, it’s hard to be a (more...)
Every so often I have a nose around the contents of the Oracle Linux public yum repositories and guess what I found in the OL7.1 base and OL7 latest repositories.
The datestamps suggest they’ve been around since the 5th February, but I think these only became available with the release of OL7.1.
check the sysman and dbsnmp account status, If expired, please activate
SQL> select username,account_status from dba_users where username =’SYSMAN';
SQL> select username,account_status from dba_users where username =’DBSNMP';
So sysman account has been expired. Please activate with old password and also Please check if this account has been locked, please unlock this account.
SQL> alter user sysman identified by Admin123;
Quite often I learn of a system where “nobody changed anything” and suddenly the system is experiencing some strange behavior. Then after diligent investigation it turns out someone changed a little parameter at the System level, but somehow disregarded mentioning it since he/she thought it had no connection to the unexpected behavior. As we all know, System parameters are big knobs that we don’t change lightly, still we often see “unknown” changes like the one described.
photo by Jose Maria Cuellar (CC 2.0)
Thanks to Leighton Nelson who pointed out that :
Oracle has a pre-installed Linux VM with 12c
Delphix as well has a pre-installed trial version
Download both of these and start them up in Virtualbox and you can start virtualizing your PDBs.
The Oracle pre-installed VM has a few eccentricities that have to be addressed before using it. There is no IP address and there (more...)
I tested this in an Oracle 12.1 database. The V$BACKUP view tells you if a datafile is in hot backup mode. I started off with none of the datafiles in hot backup mode so they were all shown as NOT ACTIVE:
SQL> select file#, status from v$backup
1 NOT ACTIVE
2 NOT ACTIVE
3 NOT ACTIVE
5 NOT ACTIVE
If your company has a passing interest in database security, you are probably running some sort of session auditing at the very least [audit session] (although this can also be useful for troubleshooting connectivity issues). There’s a reasonable chance you’re also running some level of object auditing, or even DML access auditing if your employer so dictates:
Check access/change of objects in the DB
1 select audit_option, success, failure
2 from dba_stmt_audit_opts
Changing ownership of Named Credentials is quick and easy. I’d created a Named Credential under my own OEM account and decided to share it with SYSMAN so we could set it as the Preferred Credential for a certain class of targets across the enterprise.
While logged in as the current owner, traverse down through Setup | Security | Named Credentials to this screen:
Highlight the Named Credential and press the Manage Access button to bring up (more...)
Here are the slides of a presentation I did at the IOUG Virtual Exadata conference in February. I’m explaining the basics of some new Oracle 12c things related to Exadata, plus current latest cellsrv improvements like Columnar Flash Cache and IO skipping for Min/Max retrieval using Storage Indexes:
Note that Christian Antognini and Roger MacNicol have written separate articles about some new features:
Before discussing the Exadata-specific feature, let’s review what the database engine can do independently of whether Exadata is used. To execute queries containing the
max functions efficiently, two specific operations are available with B-tree indexes defined on the column referenced in the
max function. The first,
INDEX FULL SCAN (MIN/MAX), is used when a query doesn’t specify a range condition. In spite of its name, however, it performs no full (more...)
As mentioned in a previous post, when I was at Birmingham City University (BCU) speaking at the UKOUG Next Gen event, one of the lecturers saw me and subsequently asked if I would come in and do some technical talks for the students. I did the first about a month ago. Yesterday I had the morning off work to pop across to do another talk.
This talk was on virtualization. It’s based on the slides for (more...)
This article is written with examples taken from an (virtualised) Oracle Linux 6u6 X86_64 operating system, and Oracle database version 220.127.116.11.1. However, I think the same behaviour is true for Oracle 11 and 10 and earlier versions.
Probably most readers of this blog are aware that a “map” of mapped memory for a process exists for every process in /proc, in a pseudo file called “maps”. If I want to look (more...)