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December 2012

Exadata Storage Indexes Part V: Warming Up (Here Come The Warm Jets)

As I mentioned in a previous post, there are a number of Similarities between Storage Indexes and Database Indexes. One of these similarities is the “warming up” process that needs to take place before indexes become “optimal” after either the Storage Server (in the case of Storage Indexes) or the Database Server (in the case […]

Enkitec at UKOUG 2012

Hi,

Here’s the list of Enkitec’s UKOUG conference sessions – I will be delivering 3 sessions, including a 2 hour Exadata hacking session!

We are also sponsoring the ping-pong table (woo-hoo! :) and will give away 3 super-cool Sphero balls … that should be fun! ;-)

See you soon!

 

Movember is (nearly) over…

Movember is officially over, but I’ve got to keep my Mo for a couple more days. Some people have promised donations as long as this thing is still on my face on Monday at UKOUG 2012.

It started off as fun, but now it’s a bit of an itchy nightmare. I can’t wait for Monday evening so I can see the back of it!

Thanks to everyone who donated some cash. I’m sure the relevant charities will very much appreciate your contributions!

I’ll report the final total once I know what it is, and I’ve added my donation to it.

Cheers

Send an Email From Excel, Visual Basic 6, or a Windows Command Line Using Oracle’s UTL_MAIL Package

November 30, 2012 (Back to the Previous Post in the Series) Today is this blog’s third anniversary, so to celebrate, I thought that I would share a simple code example.  As many regular readers of this blog probably know, Oracle Database 10.1 introduced the UTL_MAIL package, which allowed programs accessing Oracle Database to easily send […]

Enqueue – is it a PK, FK or Bitmap Index problem?

If one is seeing  ‘enq: TX – row lock contention’ there could be a lot of reasons. One distinguishing factor is the lock mode. If the lock mode is exclusive (mode 6) then it’s most likely a classic row lock where two sessions are trying to modify the same row. On the other hand if the lock mode is share (mode 4)  it’s typically going to be

  • inserting a unique key when  someone else has already inserted that key but not committed
  • Inserting a foreign when then parent value has been inserted but not committed or deleted and not commited (not to be confused with locks due to un-indexed foreign key which cause a “enq: TM – contention”  wait not a TX wait)
  • bitmap index chunk contention

Now how to tell which of these is happening? Well here is a query on ASH (I’ve commented out some of the useful fields to limit the output)  and a results cheat sheet: