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March 2009

Oracle 11g: Reading alert log via SQL

Oracle has done some major improvements in the diagnosability infrastructure in version 11g. Here’s one little detail.

Before Oracle 11g it is possible to access the alert log via SQL using an external table or a pipelined function which in turn uses utl_file.

After reading the text you need to parse it to extract the information you need from there.

Starting from 11g Oracle does all this work for you. There is a fixed table X$DBGALERTEXT, when you query it, Oracle reads the log.xml from alert directory (which contains all the data what alert.log does), parses it and returns the details back as rows:

Oracle 11g: Reading alert log via SQL

Oracle has done some major improvements in the diagnosability infrastructure in version 11g. Here’s one little detail.

Before Oracle 11g it is possible to access the alert log via SQL using an external table or a pipelined function which in turn uses utl_file.

After reading the text you need to parse it to extract the information you need from there.

Starting from 11g Oracle does all this work for you. There is a fixed table X$DBGALERTEXT, when you query it, Oracle reads the log.xml from alert directory (which contains all the data what alert.log does), parses it and returns the details back as rows:

Oracle 11g: Reading alert log via SQL

Oracle has done some major improvements in the diagnosability infrastructure in version 11g. Here’s one little detail.

Before Oracle 11g it is possible to access the alert log via SQL using an external table or a pipelined function which in turn uses utl_file.

After reading the text you need to parse it to extract the information you need from there.

Starting from 11g Oracle does all this work for you. There is a fixed table X$DBGALERTEXT, when you query it, Oracle reads the log.xml from alert directory (which contains all the data what alert.log does), parses it and returns the details back as rows:

Configuring VMWare on a Laptop

I have been using VMWare Server Linux VMs on my Windows XP laptop for over two years; with both single instance and RAC configurations across numerous VMs. Normally my laptop is connected to my home network (192.168.1.x) so I have been assigning VMs with IP addresses in the same subnet and configuring bridged networks. This worked OK while I was at home but I always had a problem when I was on the road and I could not find a suitable network connection. If all my adapters were reporting "media disconnected" I could not get a network connection between my host and the VMs.

I finally solved this problem (with help from Simon Haslam of Verition) last week. I have installed a Microsoft Loopback Adapter and configured a network address on this. The network address works even if the laptop is not connected to any networks.

The Microsoft Loopback Adapter can be installed using Control Panel -> Add Hardware which launches the Add Hardware Wizard

On the first page answer select "Yes, I have already connected the hardware"

On the next page select "Add a new hardware device"

On the next page select "Install the hardware that I manually select from a list (Advanced)"

On the next page select "Network adapters"

On the next page in the Manufacturer drop down select "Microsoft" and then in the Network Adapter drop down select "Microsoft Loopback Adapter"

The Loopback Adapter will be installed.

You can then specify an IP address for the loopback adapter using Settings -> Network Connections. I used 192.168.5.100 for my host; 192.168.5.0 is a new subnet in my network.

Another LatchProfX use case

Riyaj Shamsudeen wrote an excellent article about systematic latch contention troubleshooting.
Especially if the latch contention problem is ongoing, looking into system wide stats (like v$latch.sleep columns) is not the best idea in busy systems. This may sometimes lead you to fixing the wrong problem.
This is because sometimes the latch contention is not caused by some system wide inefficiency but rather by one or few sessions.
The right approach would be to measure the following things:

Another LatchProfX use case

Riyaj Shamsudeen wrote an excellent article about systematic latch contention troubleshooting.
Especially if the latch contention problem is ongoing, looking into system wide stats (like v$latch.sleep columns) is not the best idea in busy systems. This may sometimes lead you to fixing the wrong problem.
This is because sometimes the latch contention is not caused by some system wide inefficiency but rather by one or few sessions.
The right approach would be to measure the following things:

Another LatchProfX use case

Riyaj Shamsudeen wrote an excellent article about systematic latch contention troubleshooting.
Especially if the latch contention problem is ongoing, looking into system wide stats (like v$latch.sleep columns) is not the best idea in busy systems. This may sometimes lead you to fixing the wrong problem.
This is because sometimes the latch contention is not caused by some system wide inefficiency but rather by one or few sessions.
The right approach would be to measure the following things:

Another LatchProfX use case

Riyaj Shamsudeen wrote an excellent article about systematic latch contention troubleshooting.
Especially if the latch contention problem is ongoing, looking into system wide stats (like v$latch.sleep columns) is not the best idea in busy systems. This may sometimes lead you to fixing the wrong problem.
This is because sometimes the latch contention is not caused by some system wide inefficiency but rather by one or few sessions.
The right approach would be to measure the following things:

Exadata front and center

Just in case you were like me and did not tune in for Oracle’s quarterly earnings concall, there were some interesting highlights. As many of you (well, there aren’t that many of you that read this, but…) know, I’ve been very interested in Exadata since its announcement at Oracle OpenWorld 2008 in October. While some observed that Larry’s introduction keynote was rather brief, I didn’t take it as a sign of disinterest at all. According to the concall earlier this week, quite the opposite.

Here are some choice excerpts from the transcript that I find telling about the future of Exadata:

Larry Ellison:

“So, that’s looking back. Now looking forward, I think the most exciting product we’ve had in many, many years is our Exadata Database Server.”

Congratulations New Oracle ACE, Jeremy Schneider!

I’ll be the first to offer a large congratulations to Jeremy Schneider on being the most recent appointment to the Oracle ACE program. He certainly deserves it (I nominated him, so I suppose I would think so) and I continue to look for great things to come.