Tag Archives: statistics

Useful stuff from event 10053 traces – part 1

Posted on April 14, 2014 by Marcel-Jan Krijgsman

In theory you can use event 10053 traces to see what choices the optimizer has made, which is very interesting if your query didn’t perform as it was supposed to do. In practice event 10053 traces contain an overwhelming amount … Continue reading →

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Dynamic sampling NOT used for this statement?

Posted on April 8, 2014 by Marcel-Jan Krijgsman

So I’m still working on this data warehousing project and performance is not quite optimal. There are all kinds of things to be investigated. One thing I want to find, is the reason why a lot of execution plans show … Continue reading →

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Performance tuning, a medical drama – Act one

Posted on May 8, 2013 by Marcel-Jan Krijgsman

The telephone of the first responders of our DBA team rings. One of them takes up the phone and quickly scribles some notes. Apparently a severity 2 incident has been issued. Application XYZ is not well and the collegue on … Continue reading →

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More statistics history

Posted on February 19, 2013 by Marcel-Jan Krijgsman

After writing about table statistics, I tried my query to retrieve them many times. Soon I found out, I couldn’t find index statistics data. After a while I figured it out. Duh! The table is called WRI$_OPTSTAT_TAB_HISTORY. So I quickly … Continue reading →

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Table and index statistics history

Posted on February 6, 2013 by Marcel-Jan Krijgsman

As a performance tuning DBA I regularely get questions about query performance gone bad. Often you get to hear that everyone was minding their own business and certainly did not change the application code or anything, when suddenly, from one … Continue reading →

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