Yesterday and today I’ve read or heard two people mention the force_match => TRUE parameter value for DBMS_SQLTUNE.IMPORT_SQL_PROFILE and how it forces a profile to work on all SQL statements that are the same except for their literal values. So, I ran a quick test using the coe_xfr_sql_profile.sql utility that comes with the SQLT scripts that are available for download on Oracle’s support site.
I’ve mentioned in earlier posts how we use (more...)
Here is a series of Oracle performance tuning videos that I put together recently at Delphix. All the presentations are free and open to the public, just have to register.
Successfully managing a modern organization’s complex data estate requires careful work at multiple layers, from the implementation of organization-wide data policies and platforms to the careful tuning of particular databases. Only with optimization at every level can data achieve its full potential, enabling the (more...)
I recall that the Dec 1999 or Jan 2000 issues of Nat’l Geographic magazine had a “Letters From The Editor” column that speculated, in jest, that the rate at which humans were saving back-issues of Nat’l Geographic magazine, would by the year 2100 result in the total accumulation of yellow magazines outweighing planet Earth.
Anyway, that statement resonated with me, because although I change residences every few years, it has only been (more...)
John Beresniewicz and I worked hand in hand on developing the performance pages in Oracle Enterprise Manager. John is one of the foremost experts on active session history (ASH) queries and he has recently posted some of his presentations on ASH to slideshare:
This graph represents commit time compared to CPU utilization and redo log write time. I’ve included only the hourly intervals with more than 1,000,000 commits. At these peaks the number of commits ranges 1 to 1.6 million commits per hour so each point on the graph represents roughly the same commit rate. I’m puzzled by why the commit time bounces around peaking above 5 milliseconds when I can’t see any peaks (more...)
Programmers have a head start over the rest of humanity in leading happy, meaningful lives. If you have not yet reached complete enlightenment, I encourage you to sign up and invest 30 minutes listening to this call. It might improve your life.
I wanted to expand on a thread in a LinkedIn group I’m part of, where one of the members wrote “It’s funny when 2 experts are arguing about who is better”, using Tom Kyte and Jonathan Lewis as examples of people they say are “Experts”.
Disclaimer: I have not spoken to Jonathan or Tom in regard to their viewpoints on this subject, so this shouldn’t be taken as them saying any of this, just my (more...)
I am learning about how well commits scale on Oracle 11.2 and so far they seem to scale surprisingly well.
I’ve looked at two waits – log file parallel write and log file sync. Based on documents I’ve read on Oracle’s support site log file parallel write represents the time it takes to do one write to the redo logs. For mirrored redo logs the log file parallel write time includes the (more...)
While 8k is the default block size, Oracle supports other block sizes, too. Smaller block sizes (more commonly, 4k) are encouraged for OLTP workloads to reduce concurrency, and even smaller block size, 2k, is recommended for databases running on “Advanced format” (or “4K”) storage. Oracle documentation warns us of possible implications when storing larger rows in 2k/4k blocks, such as potentially larger space overhead due to metadata, or even possibility of row chaining. What it (more...)
Anyone who has used Oracle for a while will be familiar with the Parent/Child locking "issue" when it comes to tables and indexes on foreign keys. For many years you’d hear people crying "bug" etc but thankfully most now know the reason, and accept it as sensible behaviour.
But lets take a look at a slight variation on that theme.
Lets start with a table called "LOC" which will be our parent table in (more...)
The main force of this book is that it explains the publishing industry from the inside: What a publisher is looking for. The authors honestly explain what the publisher will and will not do, and that (more...)
I’ll be going to the UKOUG Tech 14 conference in Liverpool in December to give one of my favorite presentations: “APEX or ADF? From Requirements to Tool Choice”. I’m also leading the Development Tools roundtable, which is always lively at the UKOUG conference. If you want to discuss your options as a developer in the Oracle world, UKOUG Tech 14 is the place to be.
People ask me to justify use of Delphix. I can understand. Delphix is pretty new and often, most of my friends who are DBAs respond with “I can copy a database, so what, I can do it a little faster with Delphix.” Well that’s missing the whole boat. The question won’t be why you should use Delphix but “can you justify working without Delphix?”
I see Delphix as amazingly positioned at nexus of data (more...)