Chuck Hollis, VP and Global Marketing CTO at EMC has written a couple blog posts offering his thoughts on Oracle Exadata. The first was “Oracle Does Hardware” which he wrote the day after the product launch. The second, unimpressively titled “I Annoy Kevin Closson at Oracle” was on Monday October 20th which was in...
VLDB
Oracle 11g: Incremental Global Statistics On Partitioned Tables
Previously I blogged about the new and improved DBMS_STATS.AUTO_SAMPLE_SIZE used to calculate NDV in Oracle 11g and now I wanted to touch on another new feature of DBMS_STATS in 11g: Incremental Global Statistics On Partitioned Tables. Before Incremental Global Stats (Two-Pass Method) When DBMS_STATS.GATHER_TABLE_STATS collects statistics on a partitioned table, generally it does so...
Using Bitmap Indexes Effectively
Recently I was reading this thread, “Trying to make use of bitmap indexes” on the Oracle Forum. Before I had finished a working example, Jonathan Lewis had posted his response which was on par with my thoughts. Since this is a topic I see frequently, I thought I would finish my experiment and publish...
Top Ways How Not To Scale Your Data Warehouse
Working in the Real-World Performance Group at Oracle has allowed me to see quite a few customers’ data warehouses. Unfortunately some customers find their data warehouse suffering from performance problems, not because there is a platform issue, but often because the features are not used or are not used correctly. I thought I’d put...
There Is No Time Like '%NOW%' To Use Dynamic Sampling
I recently came across a query in which the Optimizer was making a poor cardinality estimate, which in turn caused inefficient join type, which in turn caused the query to run excessively long. This post is a reenactment of my troubleshooting. The Suspect SQL The original SQL was quite large and had a fairly...
The Real-World Performance Group: Oracle OpenWorld 2007 Recap
Oracle OpenWorld 2007 has come and gone and from the Real-World Performance Group’s perspective we’d consider it a successful one. The content of this year’s presentations seems to have gone over quite well as shown by the number of hallway comments and emails we received. At least two Oracle bloggers have put up their...
Oracle 11g: Extended Statistics
In the Real-World Performance Roundtable, Part 2: The Optimizer, Schema Statistics, SQL Tuning at Oracle OpenWorld 2006, I worked an example of how the optimizer can have difficulty estimating the correct cardinality when there is data correlation. (The Zodiac example can be found on pages 46-49 of the presentation.) In Oracle 11g, there has...
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