In my previous post, I made the comment:
In general, if you have a three-column index that starts with the same columns in the same order as the two-column index then the three-column index will be bigger and have a higher clustering_factor.
So what scenarios can you come up with that fall outside the general case ?
Alternatively, what argument could you put forward that justifies the general claim ?
I’ll try to respond to comments on this post a little more quickly than the last one, but I still have quite a lot of other comments to catch up on.
Database is getting high waits on buffer busy waits. Here is an example period where 5 sessions are completely blocked on buffer busy waits for 4 minutes:
select to_char(min(sample_time),'HH24:MI') maxst, to_char(max(sample_time),'HH24:MI') minst, count(*), session_id, ash.p1, ash.p2, ash.SQL_ID, blocking_session bsid from DBA_HIST_ACTIVE_SESS_HISTORY ash where event='buffer busy waits' and session_state='WAITING' group by session_id ,sql_id ,blocking_session ,ash.p1 ,ash.p2 Order by 1 /
If you are not familiar with R, this is the description from the R site: R is a language and environment for statistical computing and graphics. I encountered R at the Erasmus university, where I am working on a project with DNA data which is put in an Oracle database (see: http://huvariome.erasmusmc.nl/ (It’s down at the moment)).
I recently bought myself a Kindle – the keyboard 3G version. Keyboard as I know I will want to add notes to things and the 3G version for no better reason than some vague idea of being able to download things when I am away from my WiFi.
So, how about getting Oracle documentation onto it? You can get the oracle manuals as PDF versions (as opposed to HTML) so I knew it was possible and that others have done so before. A quick web search will show a few people have done this already – one of the best posts is by Robin Moffat.
Anyway, this is my take on it.
I will make an first time attempt tomorrow to do a webcast for ODTUG in the US about how to start with XML in the Oracle database kind of topics. The subject was initially inspired by Cary Millsap’s great whitepaper, “Thinking Clearly About Performance”, that is, my attempt of doing an OakTalk during UKOUG 2011.
I mentioned this when I blogged about my 11gR2 Virtual RAC install on Windows 2008. It came up in a conversation with Niall Litchfield at UKOUG 2011 and I’m reminded of it again today, after doing an 11gR2 install on Windows XP to double-check my answer to a question. Oracle database installs on Windows are so incredibly easy!
Now I’m not saying I would want to run Oracle on Windows out of choice. I’m a Linux fanboy, as you probably know, but even the most staunch Linux fan would have to agree that Oracle installs on Linux require quite a few prerequisite steps, even with the oracle-validated package. There is just nothing to do on Windows except put in the CD (iso image) and go…
In my previous post on Index Organized Tables (IOT), I introduced the concept of the IOT Overflow Segment, where we can store columns that we may not want to include within the actual IOT index structure. Before we move on, I just wanted to cover off a few additional points that could be a trap for the [...]
One of the promises from Oracle for OEM 12c was improved support for Oracle RAC One Node. I have spent quite a bit of time researching RON, and wrote a little article in 2 parts about it which you can find here:
One of my complaints with it was the limited support in OEM 11.1. At the time I was on a major consolidation project, which would have used OEM for management of the database.
Just a quick heads-up for anyone who is interested in getting hold of a free copy of
OCA Oracle Database 11g: SQL Fundamenta
There are two free e-books to be won. The two people that contact Sunil Chakravarthy (firstname.lastname@example.org) giving the best reason why they want a free copy of this book win.
Please don’t contact me about this offer. It’s not my book and it’s not my competition. Good luck.