Category Archives: Oracle

count(*) – again !

Because you can never have enough of a good thing.
Here’s a thought – The optimizer doesn’t treat all constants equally.  No explanations, just read the code – execution plans at the end:

SQL> drop table t1 purge;

Robert G. Freeman on Oracle 2015-01-07 21:56:12

Note: Something happened to this original copy of this post. I’m not sure what it was, but somehow it was like a draft copy ended up being posted and it lost almost half it’s content. I have re-created the post. So, for those of you who saw the earlier…

Recommended Reading: Oracle Database 12c NUMA-Related Topics

This is a short post to recommend some recent blog posts by Nikolay Manchev and Bertrand Drouvot on the topic of Oracle Database 12c NUMA awareness.
Nikolay provides a very helpful overview on Linux Control Groups and how they are leveraged by Oracle D…

Flashback Data Archive Enhancements in Oracle Database 12c

Having played around with Flashback Data Archive in 11g, I figured I would get through the 12c enhancements pretty quickly. I didn’t account for the fact I’m a donkey and can’t see the wood for the trees. Luckily, I know some people w…

Most Recent

There’s a thread on the OTN database forum at present asking for advice on optimising a query that’s trying to find “the most recent price” for a transaction given that each transaction is for a stock item on a given date, and e…

Performance Problems with Dynamic Statistics in Oracle 12c

I’ve been making some tests recently with the new Oracle In-Memory option and have been faced with an unexpected  performance problem.  Here is a test case:
create table tst_1 as
with q as (select 1 from dual connect by level <= 100000)…

Adaptive Query Optimization in Oracle Database 12c

Over the holiday period I finally decided to tackle the Adaptive Query Optimization stuff in Oracle 12c, which resulted in these articles.

Adaptive Query Optimization in Oracle Database 12c Release 1 (12.1) : A links page to the other articles.

2014 Year in Review

As many bloggers and sites do this time of the year, here is my review of 2014. It was a great year and it was a lot of fun, as well as educational reviewing all the data.
DBAKevlar Blog
Busiest Day on my Blog:

Posts this year:

Most popular post of 2…

UKOUG Annual Conference (Tech 2014 Edition)

The conferenceThis year the UKOUG’s tour of Britain’s post-industrial heritage brought the conference to Liverpool. The Arena & Convention Centre is based in Liverpool docklands, formerly the source of the city’s wealth and now a touristic playground …