Recently I’ve been combating a high water mark enqueue wait (enq: HW – contention) on a single node within an Exadata I’m supporting. I first noticed the wait when I was looking at the performance page for the node in Oracle Enterprise Manager 12c. What I noticed was the a lot of brown looking spikes (Image 1). These spikes correspond to a Configuration wait.
When I clicked on Configuration in (more...)
This is going to be another one of those posts, a bit like this one, that discuss the use of Oracle’s database product with Advanced Format devices. I wish there weren’t so many of these posts, but it seems that Oracle has a lot of issues with it’s implementation of 4k support.
(Before reading on, if you aren’t sure what I’m talking about here then please have a read of this page…)
Oracle Enterprise Manager 12c is a great monitoring tool for the enterprise, I think I’ve said that more than once over the last two years; however, with every release small yet simple things change. It is always the small things that will get you. I had setup monitoring for a client using monitoring templates within OEM12c; everything was being monitored, so I thought! I got a call from my client asking why (more...)
After a presentation by Lucas Jellema I decided to try something with types in Oracle. One of the issues posed in this
presentation was that the type cannot self-reference. Neither direct nor indirect.
A table like the emp table cannot be expressed as an object type. The table has a column mgr which is a reference to another employee.
So I tried something like this:
TYPE emp_t AS OBJECT
( empno number(4)
, ename (more...)
This article is about the use of Advanced Format devices on Oracle’s ASMLib kernel library for Linux. For background, read this page on 4k sector sizes first, otherwise it might all sound like nonsense. Mind you, it mind sound like nonsense anyway, I can’t guarantee anything here. By the way, a big hello to my buddy Nate who asked for this information: you rock, dude.
In more recent versions of ASMLib, Oracle introduced a new (more...)
One consequence of my job is that I spend a lot of time looking at Oracle Automatic Workload Repository reports, specifically at information about I/O. I really do mean a lot of time (honestly, I’m not kidding, I have had dreams about AWR reports). One thing that comes up very frequently is the confusion relating to how the measurements of IOPS and throughput are displayed in the AWR report Load Profile section. The answer, (more...)
Result cache is a powerful tool to gain performance in PL/SQL.
There are many examples on the internet that proves this, e.g. these articles on All things Oracle:
- Result Cache(1)
- Result Cache(2)
But I’m not going to talk about performance.
This article is some kind of warning.
First I’ll show you how result cache works on a normal view.
I’ll create a table, a view on this table and a function that (more...)
From time to time, when working at various sites I have to check connections to a database. If you have been an Oracle DBA for some time, you already know that the listener has to be up and services have to be registered before you can connect from a remote host. If the listener is up and services are registered, then you should be able to get to the database; so why the (more...)
Recently, I have had conversations with users about Oracle Database 12c. One question that often comes up is, how does the database manage the parameters between a container database (CDB) and a pluggable database (PDB)? In order to answer this question, I had to work with my pluggable database setup in a test environment. Before changing anything within my database setup I first made a backup of the current parameters using a (more...)
Just a quick note to highlight that the Oracle pre-built Developer VMs have been updated for Oracle 12c.
Oracle pre-built Developer VMs
As anyone familiar with the use of Oracle on Advanced Format storage devices will know to their cost, Oracle has had some difficulties implementing support of 4k devices. Officially, support for devices with a 4096 byte sector size was introduced in Oracle 11g Release 2 (see section 188.8.131.52 of the New Features Guide) but actually, if the truth be told, there were some holes.
(Before reading on, if you aren’t sure (more...)
In this post, I’m installing the Oracle Database 11g Release 2 (184.108.40.206) software on Oracle Linux 6.4, along with optional instructions on how to apply the latest Patch Set Update (PSU) to your new Oracle home. First and foremost, before you start, make sure your Linux server meets the minimum hardware requirements: 1GB of RAM (plus
When adding an Exadata to Oracle Enterprise Manager 12c (OEM), it is pretty easy yet at times you may run into a problem or two. Many of these problems can be minimized by using the Oracle Enterprise Manager 12c: Exadata Discovery Cookbook (cookbook). The cookbook can be found here, so you don’t have to search to far for it.
As with adding any target in OEM, you add the Exadata the same (more...)
Picture courtesy of Capsun Poe
Storage for DBAs: Do you want to sell your house? Or your car? Let’s go with the car – just indulge me on this one. You have a car, which you weren’t especially planning on selling, but I’m making you an offer you can’t refuse. I’m offering you one million dollars so how can you say no?
The only thing is, when we come to make the trade I (more...)
Warning: This one may be longer than normal
How many times have you ran an exachk, produced the text file, and then had to either read the file on the compute node or copy it to your local machine? Well there is another way to view the report of the EXACHK; it can even be ran on a timely basis so you have current EXACHK information on a regular basis. What I’m talking (more...)