Oracle

dbakevlar's picture

Metric Thresholds and the Power to Adapt

Metric thresholds have come a long way since I started working with OEM 10g.  I remember how frustrating it could be if an ETL load impacted the metric values that had to be set for a given IO or CPU load for a database when during business hours, a much lower value would be preferable.  Having to explain to the business why a notification wasn’t sent during the day due to the threshold set for resourc

oraclebase's picture

OTN APAC Tour 2014 : It’s Nearly Here!

airplane-flying-through-clouds-smallIn a little less than a week I start the OTN APAC Tour. This is where I’m going to be…

  • Perth, Australia : November 6-7
  • Shanghai, China : November 9
  • Tokyo, Japan : November 11-13
  • Beijing, China : November 14-15
  • Bangkok, Thailand : November 17
  • Auckland, New Zealand : November 19-21

Just looking at that list is scary. When I look at the flight schedule I feel positively nauseous. I think I’m in Bangkok for about 24 hours. It’s sleep, conference, fly. :)

After all these years you would think I would be used to it, but every time I plan a tour I go through the same sequence of events.

Jonathan Lewis's picture

First Rows

Following on from the short note I published about the first_rows optimizer mode yesterday here’s a note that I wrote on the topic more than 2 years ago but somehow forgot to publish.

I can get quite gloomy when I read some of the material that gets published about Oracle; not so much because it’s misleading or wrong, but because it’s clearly been written without any real effort being made to check whether it’s true. For example, a couple of days ago [ed: actually some time around May 2012] I came across an article about optimisation in 11g that seemed to be claiming that first_rows optimisation somehow “defaulted” to first_rows(1) , or first_rows_1, optimisation if you didn’t supply a final integer value.

Jonathan Lewis's picture

First Rows

I received an email earlier on this year asking me my opinion of the first_rows option for the optimizer mode. My correspondent was looking at a database with the following settings:

optimizer_mode=first_rows
_sort_elimination_cost_ratio=4

He felt that first_rows was a very old optimizer instruction that might cause suboptimal execution plans in it’s attempt to avoid blocking operations. As for the cost ratio, no-one seemed to be able to explain why it was there.

He was correct; I’ve written the first_rows option a few times in the past – it was left in for backwards compatibility, and reported as such from 9i onwards!

marco's picture

Download Oracle VirtualBox VM with Database version 12.1.0.2

Somehow missed the announcement that the Oracle Development team refreshed (9/26/2014) the VirtualBox Oracle Database…

oraclebase's picture

Oracle ACE Program: Follow Up

I just wanted to write something as a follow up to my recent and provocatively titled Oracle ACE = Oracle’s Bitch? post. Obviously, that subject has been preying on my mind a little… I said before, it is hard to be objective about yourself, so maybe some aspects of the “being an Oracle ACE changes you” debate may be true. It would be wrong of me to deny that outright, but I think there are some indirect consequences of being an ACE that might alter my opinions about things, so I thought I would share my thoughts…

Access to Information

marco's picture

Ordina Open Wereld 2014

Werelds grootste IT conferentie, Oracle OpenWorld in San Francisco is voorbij. Meerdere Ordina mensen zijn…

oraclebase's picture

Pattern Matching (MATCH_RECOGNIZE) in Oracle Database 12c

I’ve spent the last couple of evenings playing with the new SQL pattern matching feature in Oracle 12c.

I’m doing some sessions on analytic functions in some upcoming conferences and I thought I should look at this stuff. I’m not really going to include much, if anything, about it as my sessions are focussed on beginners and I don’t really want to scare people off. The idea is to ease people in gently, then let them scare themselves once they are hooked on analytics. :) I’m thinking about Hooked on Monkey Fonics now…

oraclebase's picture

Oracle ACE = Oracle’s Bitch?

I got a comment today on my recent Oracle fanboy post, which I thought was very interesting and worthy of a blog post in reply. The commenter started by criticising the Oracle license and support costs (we’ve all had that complaint) as well as the quality of support (yes, I’ve been there too), but that wasn’t the thing that stood out. The final paragraph was as follows…

“One addition. I know you, your past work and you are very brainy person but since last couple of years you became Oracle doctrine submissive person just like most of the rest of ACE Directors. When you were just ACEs, you were more trustworthy than now and you weren’t just Oracle interpreters… And unfortunately I’m not the only person with this opinion, but probably I’m only one who is not affraid to make it public.”

Jonathan Lewis's picture

Deadlocks

A recent question on the OTN forum asked about narrowing down the cause of deadlocks, and this prompted me to set up a little example. Here’s a deadlock graph of a not-quite-standard type:

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