Speaking at OOW 2016: Write powerful scripts with EMCLI

This will be my first time to attend Oracle Open World, and I’ll speak about Enterprise Manager Command-Line Interface (EMCLI) Scripting” on User Group Sunday. I already presented it on several conferences, heard people’s feedback and modified the content to improve my presentation. Now I will focus more on practical information, share sample scripts that can be used in real world scenarios. Hope to see you there!

Session ID: UGF3543
Session Title: Oracle Enterprise Manager (more...)

How Many ASM Disks Per Disk Group And Adding vs. Resizing ASM Disks In An All-Flash Array Environment

I recently posted a 4-part blog series that aims to inform readers that, in an All-Flash Array environment (e.g., XtremIO), database and systems administrators should consider opting for simplicity when configuring and managing Oracle Automatic Storage Management (ASM).

The series starts with Part I which aims to convince readers that modern systems, attached to All-Flash Array technology, can perform large amounts of low-latency physical I/O without vast numbers of host LUNs. Traditional storage (more...)

Maintaining disabled FK’s, wisdom or farce?

A while back, I wrote a post about having FKs (foreign keys) in your data warehouse. Well, a similar question came up recently on an Oracle forum with the above title. It is a fair question and it does surface fairly regularly in a variety of contexts (not just data warehousing). Of course, as The […]

An excellent review of where we are, where it all came from, and where we are going‏

About the book he reviewed for the August 2016 issue of the NoCOUG Journal, Brian had this to say: “You should read this book. If you are starting out in a database-related career—which I think includes most, if not all, programming jobs—or if you are changing fields within the broader database field, the information in this book will be very helpful in the interview and on the job. I learned a great deal about things (more...)

A day in the life of a problem solver

P.O.I.S.E.D. is the acronym I invented for the performance tuning method described by Chris Lawson in The Art and Science of Oracle Performance Tuning; it stands for Problem, Observation, Interpretation, Solution, Execution, and Documentation.(read more)

Conference Report: NoCOUG 2016 summer conference at Chevron

The Northern California Oracle Users Group (NoCOUG) is a volunteer-run 501(c)(3) organization and the longest-running Oracle users group in the world. It organizes a full-day conference every quarter and publishes a quarterly Journal. The summer conference at Chevron was the 119th quarterly conference organized by NoCOUG.(read more)

An introduction to Oracle PL/SQL for beginners

PL/SQL offers the entire suite of structured programming mechanisms, such as condition checking, loops, and subroutines, as shown in the following figure. (read more)

Parallel_index hint

Prompted by a recent OTN posting I’ve dug out from my library the following demonstration of an anomalty with the parallel_index() hint. This note is a warning about  how little we understand hints and what they’re supposed to mean, and how we can be caught out by an upgrade. We’ll start with a data set which, to match a comment made in the origina posting rather than being a necessity for the demonstration, has an (more...)

Resizing ASM Disks On Modern Systems. Real Application Clusters Doesn’t Make It Any More Difficult. An XtremIO Example With RAC.

My recent post about adding space to ASM disk groups by resizing them larger, as opposed to adding more disks, did not show a Real Application Clusters example. Readers’ comments suggested there is concern amongst DBAs that resizing disks (larger) in a RAC environment might somehow be more difficult than in non-RAC environments. This blog entry shows that, no, it is not more difficult. If anything is true it is that adding disks to ASM (more...)

Simple Cold Backup using tar

At times, I find it much simpler to shutdown my test database and create cold backup which will allow me to revert from any errors.

$ echo $ORACLE_SID

$ tar -cvzf /media/sf_OracleSoftware/$ORACLE_SID_$USER_`hostname -s`_backup.tar.gz .

$ ll /media/sf_OracleSoftware/DB01_oracle_arrow_backup.tar.gz
-rwxrwx---. 1 root vboxsf 382676286 Aug 28 13:09  (more...)

Are analytic RDBMS and data warehouse appliances obsolete?

I used to spend most of my time — blogging and consulting alike — on data warehouse appliances and analytic DBMS. Now I’m barely involved with them. The most obvious reason is that there have been drastic changes in industry structure:


A huge thank you to Pete Finnigan for his blog post.

Hacking Oracle 12c COMMON Users

Not only is the implementation of ORACLE_MAINTAINED not ideal, it’s a possible security risk.

My tip to you is to always exit the session before performing any object creation.

From my pain as you can see, looks like “_ORACLE_SCRIPT was not reset when new users where created.

Also ORACLE_MAINTAINED Objects Don’t Export

Learned quite a few new thing this weekend and (more...)

ORACLE_MAINTAINED Objects Don’t Export

What a disaster this is with 12c full database export and ORACLE_MAINTAINED objects.

Somehow, oracle thinks MDINH is an ORACLE_MAINTAINED user and user MDINH does not get exported.


Why Can an Object Not Be Exported? Expdp of SYSTEM User’s Table Returns ORA-39166 or ORA-31655 (Doc ID 2114233.1)

There are certain system generated schemas that are not exportable using exp or expdp because they contain Oracle-managed data and metadata. SYS, MDSYS, and ORDSYS are some (more...)


I recently discovered about column ORACLE_MAINTAINED added to DBA views and got excited over nothing.

Denotes whether the role was created, and is maintained, by Oracle-supplied scripts (such as catalog.sql or catproc.sql).
A role for which this column has the value Y must not be changed in any way except by running an Oracle-supplied script.

It looks like ORACLE_MAINTAINED is only valid for CDB and seems as if Oracle is really wanting all (more...)

EM13c: Performance Tuning Access to Read Only Administrators

About six months ago, when I was in the OUGN Spring Conference, someone asked me how they can let developers access to performance tuning pages on Enterprise Manager Cloud Control 13c. He said that they granted full administrator privileges to the developers so they could access the performance page but it’s not acceptable. He also mentioned that they didn’t need to grant full administration privilege to the developers’ EM users while they were using (more...)

Little things worth knowing: using Remote Diagnostic Agent more effectively with profiles

RDA, or the Remote Diagnostics Agent, has been around for a little while. Over the time, and with the growing number of Oracle’s acquisitions it has become, shall we say, a little more difficult to handle. It appears to me as if every one of them will have its diagnostics handled by RDA making it hard to focus on something specific, like for example the database.

I won’t go into very detail of the Remote (more...)

How to Import Data (to Oracle RDBMS) from XML

I wrote a blog post about how to import data from a XML file to Oracle about 7 years ago. I demonstrated how we can use DBMS_XMLSTORE package to parse XML data. Yesterday, I replied a question from a blog reader about that post. He had problem with running my sample script, I did troubleshoot and find out the problem with his script, and while testing the sample script, I noticed that I can write (more...)

Grid Infrastructure 12c installation fails because of 255 in the subnet ID

I was doing another GI cluster installation last month when I got really weird error.

While root.sh was running on the first node I got the following error:

2016/07/01 15:02:10 CLSRSC-343: Successfully started Oracle Clusterware stack
2016/07/01 15:02:23 CLSRSC-180: An error occurred while executing the command '/ocw/grid/bin/oifcfg setif -global eth0/ eth1/' (error code 1)
2016/07/01 15:02:24 CLSRSC-287: FirstNode configuration failed
Died at /ocw/grid/crs/install/crsinstall.pm  (more...)

Basicfile LOBs 4

At the end of the previous installment we saw that a single big batch delete would (apparently) attach all the “reusable” chunks into a single freepool, and asked the questions:

  • Why would the Oracle developer think that this use of one freepool is a good idea ?
  • Why might it be a bad idea ?
  • What happens when we start inserting more data ?

(Okay, I’ll admit it, the third question is a clue about the answer (more...)

G-Cloud – Moving Your Oracle System to Amazon Web Services

G-Cloud was awarded a few weeks ago and we're glad to say that clckwrk were selected as a supplier in the areas of Infrastructure as a Service and Specialist Services.

The services we have on G-Cloud are specifically curated for implementing, moving and managing Oracle systems to the cloud. This is a quick guide for how to combine those services to migrate to the cloud. For public sector users of Oracle technology and applications this is the set (more...)