Video Tutorial: XPLAN_ASH Active Session History – Part 6

The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality continuing the actual walk-through of the script output.

More parts to follow.

Native Network Encryption and SSL/TLS are not part of the Advanced Security Option

I had a little surprise the other day. I was asked to set up a SSL/TLS connection to a database and I refused, saying it would break our license agreement as we don’t have the Advanced Security Option. I opened the 11gR2 licensing manual to include a link in my email response and found this.

“Network encryption (native network encryption and SSL/TLS) and strong authentication services (Kerberos, PKI, and RADIUS) are no longer part of (more...)

The technology community

I remember on a flight to the UKOUG, I was doing what all presenters typically do on a plane.  They enter the cabin with the thought of "OK, I’ll spend most of the flight getting those slides just right".  Then…a set of broadcast advertisements, safety messages, hot face towels, exit row briefings, beverage services, coffee services, and before you know it you’ve burned 2 hours without touching the laptop…and then the meal service (more...)

Kscope15, a celebration of tech…

Kscope15 promised to be a brand new experience in more than one way.

Kscope15LogoAs I start to write this report, I am flying from Düsseldorf airport to Atlanta. It will be the first time flying to the United States with a stopover, and because of Erik van Roon, I came prepared. With just carry-on luggage, I should end up at my final destination, Fort Lauderdale, Florida, together with my ‘stuff’. I am flying Delta (more...)

SQL*Plus tips #7: How to find the current script directory

You know that if we want to execute another script from the current script directory, we can call it through @@, but sometimes we want to know the current path exactly, for example if we want to spool something into the file in the same directory.
Unfortunately we cannot use “spool @spoolfile”, but it is easy to find this path, because we know that SQL*Plus shows this path in the error when it can’t (more...)

Friday Philosophy – At What Point Can You Claim a Skill?

I’ve just installed Oracle 12C on my laptop {I know, why only now?}. I went for the option to have a Container database with a pluggable database within it. {It is easy and free to install Oracle on your own home machine – so long as it is for personal use only and you are singed up to OTN (which is also free) }.

12C with pluggable databases (PDBs) is a little different to (more...)

Log Buffer #429: A Carnival of the Vanities for DBAs

This Log Buffer Edition gathers a wide sample of blogs and then purifies the best ones from Oracle, SQL Server and MySQL.


  • If you take a look at the “alter user” command in the old 9i documentation, you’ll see this: DEFAULT ROLE Clause.
  • There’s been an interesting recent discussion on the OTN Database forum regarding “Index blank blocks after a large update that was rolled back.”
  • 12c Parallel Execution New Features: 1 (more...)

If EMD_MAINTENANCE.DISABLE_EM_DBMS_JOBS Hangs When Deconfiguring Plug-In from Management Repository

Today, I tried to remove a plugin from Management Server but I see that undeployment process was hung at step 5:

----------------------------- ----------------------- -------------------------
Step                          Start Time              End Time                  
----------------------------- ----------------------- -------------------------
Submit job for undeployment   6/26/15 8:39:07 AM EEST 6/26/15 8:39:07 AM EEST Success

Initialize                    6/26/15 8:39:23 AM EEST 6/26/15 8:39:24 AM EEST Success

Validate plug-in home         6/26/15 8:39:25 AM EEST 6/26/15 8:39:27 AM EEST Success

Delete plug-in's metadata     6/26/15 8:39:28 AM EEST 6/26/15  (more...)

Is it possible to cause tables to be stale with only tiny amounts of change?

I don't really like posting blog entries about Oracle statistics as so many other people do it better than i ever could (Jonathan, Randolf etc) - well that and i'm likely to get it wrong...

However i've been looking in to something today and i think it's worth sharing the results as it's quite interesting.

We have a large datawarehouse that's having stats issues (par for the course pretty much), i won't go in to (more...)

Hive (HiveQL) SQL for Hadoop Big Data

In this  post I will share my experience with an Apache Hadoop component called Hive which enables you to do SQL on an Apache Hadoop Big Data cluster.

Being a great fun of SQL and relational databases, this was my opportunity to set up a mechanism where I could transfer some (a lot)  data from a relational database into Hadoop and query it with SQL. Not a very difficult thing to do these days, actually (more...)

All Flash Arrays: What Is An AFA?

All Flash Arrays - Hybrid, SSD-based or Ground-Up

For the last couple of years I’ve been writing a series of blog posts introducing the concepts of flash-memory and solid state storage to those who aren’t part of the storage industry. I’ve covered storage fundamentals, some of what I consider to be the enduring myths of storage, a section of unashamed disk-bashing and then a lengthy set of articles about NAND flash itself.

Now it’s time to talk about all flash arrays. (more...)

Oracle Midlands : Event #10

Just a quick heads-up about the next Oracle Midlands event. It’s good to encourage new speakers, so Mike is giving this new, unknown kid a shot at the limelight. I hope you will all come along to show your support.




Oracle Midlands : Event #10 was first posted on June 25, 2015 at 9:47 am.
©2012 "The ORACLE-BASE Blog". Use of this feed is for personal non-commercial use only. If you are (more...)

Quiz Time. Why Do Deletes Cause An Index To Grow ? (Up The Hill Backwards)

OK, time for a little quiz. One of the things I’ve seen at a number of sites is the almost fanatical drive to make indexes as small as possible because indexes that are larger than necessary both waste storage and hurt performance. Or so the theory goes …   :) In many cases, this drives DBAs to […]

Why do people show Azure so much love?

cloudThe title of this post is taken from tweet I saw a few weeks ago and it keeps coming back to haunt me, so I thought I would comment on it.

Let me start by saying I don’t have any context as to why the tweeter thought people were showing Azure so much love. From my perspective, I kind-of like Azure and I think it is what my employer will end up using, but I’m not a crazed fan-boy (more...)


Global temporary table data is stored in the temporary tablespace (where no redo will be generated on the DML operations). When DML operations are performed on global temporary table, for read consistency undo must be generated. Such undo records are written to undo tablespace, and thus redo generated on the undo writes. If you perform […]

Good new SQL tuning book

People ask me from time to time what are some good SQL tuning books. It’s a tough question to answer. There are some seminal books such as “SQL Tuning” by Dan Tow and “Cost Based Optimizer Fundamentals” by Jonathan Lewis, but these are advanced books  that few I know have actually read from cover to cover. If you are looking for practical SQL tuning cookbooks you might want something a little less advanced.  For a practical (more...)

Upgraded and can’t see the tables you could before ?

If you take a look at the "alter user" command in the old 9i documentation, you’ll see this:


Specify the roles granted by default to the user at logon. This clause can contain only roles that have been granted directly to the user with a GRANT statement. You cannot use the DEFAULT ROLE clause to enable:

  • Roles not granted to the user
  • Roles granted through other roles
  • Roles managed by an external (more...)

Empty Leaf Blocks After Rollback Part II (Editions of You)

In my last post, I discussed how both 1/2 empty and totally empty leaf blocks can be generated by rolling back a bulk update operation. An important point I made within the comments of the previous post is that almost the exact scenario would have taken place had the transaction committed rather than rolled back. A […]

Large audit trail table causes high db activity – especially when using OEM

On various databases, apparently unrelated we have noticed high activity that seems to be associated with the query below. The quieter the database the more the query stands out.


SELECT TO_CHAR(current_timestamp AT TIME ZONE 'GMT', 'YYYY-MM-DD HH24:MI:SS TZD') AS curr_timestamp, COUNT(username) AS failed_count, TO_CHAR(MIN(timestamp), 'yyyy-mm-dd hh24:mi:ss') AS first_occur_time, TO_CHAR(MAX(timestamp), 'yyyy-mm-dd hh24:mi:ss') AS last_occur_time
FROM sys.dba_audit_session
WHERE returncode != 0 AND timestamp >= current_timestamp - TO_DSINTERVAL('0 0:30:00')


The detail of the audit table is that it contains 73M records (more...)

A First Technical Look At Hybrid Cloning in EM12c Release 5

The sales, support and technical teams were brought into the Denver Tech Center office to do some advanced training in Hybrid Cloud.  There were many take-aways from the days we spent in the office, (which is saying a lot-  most of you likely know how much I hate working anywhere but from home… :)) and I thought I would share a bit of this information with those that are aching for more details on (more...)