The following question came up in an email conversation a little while ago: Are you aware of any problems a large oltp site might have with running index coalesce during production hours, as opposed to doing index rebuilds in a maintenance window? The main overhead with index coalesce is that it generates a lot of [...]
If you think 16MB tables are so small that can’t be root cause of significant performance problems with SELECT queries, then read about my today’s headache – a story of 16MB table worth something like 270 seconds of response time. It began mostly as usual: an application web page didn’t show up within 5 minutes. [...]
Op donderdag 17 juni, vanaf 18:00 uur, zal Oracle Database Expert en Oracle ACE Director Doug Burns(Schotland), een kennisavond vullen met live demo’s op basis van de Oracle Enterprise Manager Diagnostic en Tuning Pack.
Deze bijzondere avond, geheel zonder slides, met de naam “How I Learned to Love Pictures – Oracle 10g/11g Performance Analysis Using OEM” zal alle in en outs van de Oracle Enterprise Manager Diagnostic en Tuning pack in geur en kleur, de valkuilen en de verstopte juweeltjes van de Oracle Enterprise Manager, demonstreren gebruik makend van onder andere Swingbench. Voor meer informatie, over Doug Burns of de inhoud van deze presentatie, zie de volgende blog posts en URL’s:
Wil je er bij zijn dan kun je je aanmelden voor deze AMIS Query, via de volgende URL:
Last week I was able to attend a 3 day exadata workshop conducted by performance engineers from Singapore. It was supposed to be a 5 day workshop with hands on labs but everything was squeezed (unfortunately no hands on) and just the critical sections were tackled.. The workshop highlight was the demos and these are as follows:
- loading large amount of data from an external table
- cell offloading on a typical datawarehouse query
- creation of a 400gb tablespace
- linear scalability of storage cells
A couple of weeks ago I tweeted a projection that the $/GB for flash drives will meet the $/GB for hard drives within 3-4 years. It was more of a feeling based upon current pricing with Moore’s Law applied than a well researched statement, but it felt about right. I’ve since been thinking some more [...]
Randolf Geist has written a good article about systematic troubleshooting of a PL/SQL memory allocation & CPU utilization problem – and he has used some of my tools too!
In the latest Quiz Night, I asked how you could make a query more efficient by changing a two table join into a three table join – with the clue that my third table was a repeat of the first table. Gary Myers, in comment 4, provided the type of answer I was looking for. Sometimes [...]
Yesterday, my 12 year-old son Alex was excited to tell me that he had learned a new trick that made it easier to multiply fractions. Here’s the trick:
Oracle 22.214.171.124 for Windows is out for some time. I’ve installed it on my 32-bit Windows XP machine because I like Windows – just to check that it’s actually working fine. Playing with TPC-H test using Hammerora I’ve noticed an anomaly in the way Oracle reports IO waits for some queries. Here is a test [...]
Here’s a little demonstration I’ve been meaning to write about for the last few years – it’s very simple: create a table, then query it a few times. execute dbms_random.seed(0) create table t1 as with generator as ( select --+ materialize rownum id from all_objects where rownum <= 3000 ) select lpad(dbms_random.string('U',2),40,'X') v1 from generator [...]