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February 2012

Dbvisit Replicate…

Last months I wrote a post Dbvisit Standby and said I planned on taking a look at their replication product at some point. I had actually already started writing an article on it, but got a bit side tracked before putting it live. I went back to it today and noticed a new version of the product had been released, so I downloaded it and gave it a run through.

What is ‘rdbms ipc message’ wait event?

Introduction

There was a question about the wait event ‘rdbms ipc message’ in Oracle-l list. Short answer is that ‘rdbms ipc message’ event means that a process is waiting for an IPC message to arrive. Usually, this wait event can be ignored, but there are few rare scenarios this wait event can’t be completely ignored.

What is ‘rdbms ipc message’ wait means?

It is typical of Oracle Database background processes to wait for more work. For example, LGWR will wait for more work until another (foreground or background ) process request LGWR to do a log flush. In UNIX platforms, wait mechanism is implemented as a sleep on a specific semaphore associated with that process. This wait time is accounted towards database wait events ‘rdbms ipc message’.

Also note that, semaphore based waits are used in other wait scenarios too, not just ‘rdbms ipc message’ waits.

Time to Trace

SQL Developer 3.1 : Scheduler Support…

I had a play around with the scheduler support in SQL Developer 3.1 today. I’m late to the party because most of it has been there since 3.0, but what the hell.

It’s more of an opinion piece, so it started as a blog post, but it got too big. Not really what I usually put on the website, but I figured if I put it on the blog it would get in the way of the movie and book reviews and that simply wouldn’t do… :)

I am still worried about feature creep turning SQL Developer into the new TOAD, but so far so good. I’m liking it more and more with each release.

Cheers

Tim…

HOTSOS 2012

I just uploaded my presentation materials for ‘Truss, pstack etc’ for HOTSOS 2012 symposium , a performance intensive conference, happening right here in my home town Dallas, TX.

I can’t believe, it is been ten years from the start of this annual conference! This is the tenth annual symposium and I have been presenting in this symposium for almost all years except few early years. Quality of presentations and quality of audience is very high in this symposium and many of the audience are repeat audience, almost this feels like an annual pilgrimage to “sanctum of performance”. If you are interested in learning the techniques and methods to debug and resolve performance issues in a correct way, you should definitely consider attending this symposium. To top it off, Jonathan Lewis is conducting Training Day this year.

My sessions in RMOUG 2012

I will be leaving to Denver in few days to talk about the following presentations in RMOUG 2012. Stop by and say hello to me if you intend to attend RMOUG training days.

My sessions in RMOUG 2012 are

  1. Room 402:Session 2: Parallel Execution in RAC – Wednesday 10:45 AM to 11:45AM
  2. Room 4f: Session 10: Troubleshooting RAC background processes – Thursday 1:30PM to 2:30PM
  3. Room 4f: Session 11: A kind and Gentle introduction to RAC – Thursday 2:45 PM to 3:45 PM

Hope to see you there.

Business: Honesty is pretty important to your customers!

My hosting company (Fasthosts) has got on my tits this morning. This is not about a service issue or anything like that. It is because they have started a new campaign promoting, amongst other things, their excellent support service…

I’ve been with the company for over 11 years. In that time their technical support has been consistently terrible for a number of reasons, including:

  • Lack of technical knowledge in first level support staff and no access to “real” technical support staff, when the first level support staff prove themselves to be complete Muppets.
  • Providing misleading, or downright wrong information.
  • Never giving a followup once issue are resolved. All you get is, “It’s working now, your ticket is closed!”
  • Excessive times before answering phones/emails when you are trying to log a ticket.

These are just the highlights, so to speak…

Hotsos 2012

I’m off to RMOUG in a couple of days time – but I’m already focused on Hotsos 2012 which is just a couple of weeks later (and I have to fit in a trip to Switzerland in between).

To stimulate some extra discussion and add value to the event, the people at Hotsos have set up an online forum about the event at http://support.hotsos.com/forum/viewforum.php?f=2   (that’s actually the follow-on address from the one they sent me, but if it works it saves you a whole click).  There’s a thread for each presentation, but at the moment there’s only one posting on each thread, and that’s the presenter’s abstract. Nearer the time, or during the symposium, I would expect to see some traffic coming in.

11.2 New views

It looks like Laimutis Nedzinskas has spent some time producing  a list of new views, and changes to existing views, for trouble-shooting specialists. The lists cover the dynamic performance views and the AWR history views, and the differences between 10.2 and 11.2. The lists include, where relevant, convenient hyperlinks to the view definitions in the online copy of  the 11g Server Reference manual.

I haven’t checked the lists in detail, but I can see myself  taking advantage of his efforts from time to time:

Session SQL

From time to time a request for a query to “show the current SQL” for each session appears on the internet. It’s not really difficult to write something suitable, but this particular request is an interesting demonstration of how much inertia there is in the Oracle world. Here’s a recent suggestion of what the query should look like:

select
        sess.sid, sess.serial#, sess.username, sess.status,
        sess.osuser, sess.machine, sess.module, sess.event,
        sess.logon_time, ss.sql_id, ss.sql_text
from
        v$session sess,
        v$sql     ss
where
        sess.sql_id   = ss.sql_id
and     sess.username = 'EFTUSER'
;

The query has an error in it that appears extremely frequently in response to this request. Can you spot what it is ? (On the plus side, the query references v$sql rather than v$sqlarea – so it’s not too nasty.)

Upcoming Speaking Engagements

I’ll be speaking at a couple of conferences over the next month or so. Here’s the schedule:

February 16th, in Denver at RMOUG Training Days 2012 - Topic: DIY Exadata
February 23rd, in Redwood Shores at NoCOUG Winter Conference - Topic: DIY Exadata
March 7th, in Dallas at Hotsos Symposium 2012 - Topic: Exadata Optimization – Case Studies