Posts by Christo Kutrovsky

Sequences in Oracle 10g RAC

I got a call from a developer who had a table with a primary key populated by a sequence, a timestamp column with the current date and some other columns. He had a specific set of data that, when ordered by the primary key had out of order timestamps. He was puzzled how this could be. We changed the sequence to “ordered” and increased the cache to 1000. Now selecting on either node gets the next number as he expected. I warned him that there would be some performance implications due to cluster synchronization. Him being a responsive developer, asked me what the impact would be, so I tested it out.

Announcing Pythian Goodies

I’ve been wondering for a while now how best to transfer knowledge efficiently and in a fun way. Presentations are good, but they require a lot of effort in preparation and research, and they are not as interactive as they could be when the group is smaller. To answer some of these issues, I would like to introduce you to Pythian Goodies. What is a Pythian Goody session you ask? Find out here.

Oracle Support Case Studies

As I was poking around metalink, I found the following extremely interesting section. It’s in a very obvious place, but it’s new, so many of you may have not noticed it. It’s called “Support case studies” and provides some amazing articles.

Diagnosing Oracle Performance Problems on *nix

One day I came up with the following neat idea. Start a second listener, on a different port, calling it the emergency listener. Then renice the listener process with higher priority. Now, every time I connect to the database via my emergency listener, my connection gets higher priority, and thus feels like there’s no problem with the database’s resource use.

There is one little caveat however. You need to either have access to root, or have a nice SA that will add renice to your sudoers file .

The Answer to Free Memory, Swap, Oracle and Everything

I have submitted an abstract for my new presentation about linux/unix memory and Oracle to the Rocky Mountain Oracle Users Group for the Training Days in Denver on February 14-15, 2007. I pilot tested it at the Ottawa Oracle User Group in June. The feedback was good and since then I have kept developing the presentation. Soon to be submitted for HotSos 2007.

Oracle: How to move a table to another schema?

A client asked me, “How can I move a table to another schema in Oracle?” The quick answer I gave him is, “not possible”. You have to rebuild it via “create table as select”. You might ask, justifiably, why would you want to do that anyway? His problem was that the application has been split into 2 parts, and he wanted to have separate schemas for each part, to ensure that there is no cross-schema table access.

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