Archive for the ‘Oracle’ Category
Thursday, August 14th, 2008
Note: Originally this experiment was from a post I wrote on the Oracle Forum: Database - General. I recommend that you read Jonathan Lewis' summarization of the thread instead of reading all 671 posts (as of today). You will spend much less time and get more out ...
Posted in Data Warehousing, Execution Plans, Optimizer, Oracle, Performance | 10 Comments »
Wednesday, July 16th, 2008
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, ...
Posted in 11gR1, Data Warehousing, Optimizer, Oracle, Statistics, VLDB | 4 Comments »
Wednesday, June 18th, 2008
With Oracle OpenWorld 2008 only a few months away, I thought I would take a moment to mention that the Real-World Performance Group will again be hosting three sessions. If you were at the sessions last year, then you probably know how good they were. If you didn't ...
Posted in Oracle | 3 Comments »
Thursday, May 29th, 2008
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 ...
Posted in 10gR2, 11gR1, Data Warehousing, Execution Plans, Optimizer, Performance, SQL Tuning, Statistics, Troubleshooting, VLDB | 6 Comments »
Thursday, May 22nd, 2008
Recently someone showed me a query execution plan with an operation of HASH JOIN ANTI NA. At first, it was thought maybe it was a bug and the operation had a type-o in it, but after further research it was discovered it was a valid operation and a new ...
Posted in 10gR2, 11gR1, Data Warehousing, Execution Plans, Optimizer, Oracle, Performance | 7 Comments »
Monday, April 28th, 2008
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 ...
Posted in Data Warehousing, Oracle, Performance, VLDB | 5 Comments »
Wednesday, March 26th, 2008
Recently the Oracle Optimizer Development Team put out a White Paper entitled Upgrading from Oracle Database 9i to 10g: What to expect from the Optimizer. This paper discusses the main differences between 9i and 10g in the subject area of the Optimizer and Statistics. As G.I. Joe ...
Posted in 10gR2, Execution Plans, Optimizer, Oracle, Statistics, Troubleshooting | 16 Comments »
Friday, March 21st, 2008
I came across this video the other day and I immediately thought of rule #3 from my Got Root Cause? post:
"Be detail oriented, but do not become too obsessed with any one detail."
Watch the video and see if you pass the Awareness Test. Most importantly, remember the punch line ...
Posted in Oracle, Troubleshooting | 2 Comments »