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March 2017

Oracle database (januari 2017 PSU) and TDE wallets

Recently, I was trying to setup TDE. Doing that I found out the Oracle provided documentation isn’t overly clear, and there is a way to do it in pre-Oracle 12, which is done using ‘alter system’ commands, and a new-ish way to do it in Oracle 12, using ‘administer key management’ commands. I am using version, so decided to use the ‘administer key management’ commands. This blogpost is about an exception which I see is encountered in the Januari 2017 (170117) PSU of the Oracle database, which is NOT happening in Oracle 12.2 (no PSU’s for Oracle 12.2 at the time of writing) and Oracle April 2016 and October 2016 PSU’s.

In order to test the wallet functionality for TDE, I used the following commands:

Oracle 12cR2: changes for login.sql

If you use a login.sql script to set the SQL*Plus environment from your current working directory, you will see that it will not run anymore in 12.2. This is a security feature, and a good occasion to explain how sqlplus finds the scritps to run, on Linux.

For my test I have login.sql, LOGIN.SQL and script.sql in the following directories

$ tree /tmp/mytest/
├── a
│   ├── login.sql
│   ├── LOGIN.SQL
│   └── script.sqlL
├── b
│   ├── login.sql
│   ├── LOGIN.SQL
│   └── script.sql
├── login.sql
└── script.sql

I’m going to the parent directory
cd /tmp/mytest

The scripts display their name:

+ head login.sql LOGIN.SQL script.sql
==> login.sql LOGIN.SQL script.sql <==
prompt Hello from /tmp/mytest/script.sql


A recent posting on the OTN database forum described a problem with an insert (as select) statement that sometimes ran extremely slowly: nothing interesting yet, there could be plenty of boring reasons for that to happen. The same SQL statement (by SQL_ID) might take 6 hours to insert 300K rows one night while taking just a few minutes to insert 900K another night (still nothing terribly interesting).

New Events for Data Guard and Synchronous Redo Transport in 12c (2)

After the baseline has been established in the first part of this series it’s time to measure the effect of the network in this part. The second test will introduce an interesting feature: Using Linux’s own Traffic Shaper/Quality of Services module I will add a delay of 100ms to the Data Guard network interface card (NIC) to slow things down a little.

WARNING: this is of course a lab or VM-only situation. I can’t exert control over wire quality in my (own) switches, hence some software magic is needed on my virtual ones. This post is intended to be merely for educational purposes, not for use at work.

I am continuing to use the 2 node RAC primary database on Oracle Linux 7 with UEK 4 and an identical RAC to host my standby database.

Delphix Company Kick Off

I had the opportunity to attend Delphix‘s Company Kick Off last week in San Francisco.  This was my first time at an event of this nature and it was incredibly successful.

Misleading wait event names clarified in V$EVENT_NAME

The oracle wait event names were originally implemented for the oracle rdbms developers and are now use by the database users to troubleshoot performance issues. The consequence is that the name may be misleading because they have a meaning from the internal point of view. Here is some clarification about them.

In 12c the clarification is easy because we have a new DISPLAY_NAME column in the V$EVENT_NAME view:

Purging Unified Audit Trail in 12cR1

When you want to empty a table you have two methods: delete and truncate. If, for any reason (see previous post) the Unified Audit Trail has become too big, you cannot directly delete or truncate the table. You must call the dbms_audit_mgmt.clean_audit_trail. But then you want to know if it will do slow deletes or quick truncates. Let’s trace it.

I have filled my Unified Audit Trail with hundred of thousands failed logins:
SQL> select unified_audit_policies,action_name,count(*) from unified_audit_trail group by unified_audit_policies,action_name;
---------------------------------------- -------------------- ----------

12c Release 2 – Transparent Data Encryption online !

It doesn’t take a rocket scientist to know that even if you have incredibly stringent controls on user authentication, user authorisation etc, that wont save you if your data on disk is not encrypted.  All you need is an errant tape, a missing disk, a misplaced flash stick…and kersplat, someone has a copy of your datafiles from your Oracle database.

Data at rest should be encrypted, but that often meant taking applications offline to do so.

I’ve put my Speed Racer hat on Smile and here’s a video on a new 12c Release 2 feature covered in 60 seconds !

New theme – it was about time

After a lot of searching and testing I have finally decided to put the ageing Andreas09 theme a rest and try a new one. It has been nagging me for years that the representation of the blog is more like the early 2000s than 201x. Or was it late 1990s? Anyway, out with the old, in with the new.

The biggest problem I have with finding suitable templates is a) that I have insufficient talent in the fine arts, and b) that I present a lot of code examples. I guess point a) can’t be helped much, but b) had to be reasonably taken care of.

The monospaced font I use in the code blocks is usually far too large-10pt or more-in most themes that I otherwise liked a lot. The current one seems to use 10pt at maximum which is a good compromise although I would have preferred 9pt. My favourite font family for coding since my MacOS 7 days is Monaco, 9pt. I wish :)