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The maximum number of bins in an Oracle frequency histogram is 254 and as we all know there are almost always more than 254 bins for frequency distributions. Oracle 12c has introduced a new concept, to help deal with the problem, the Top Frequency Histogram.
SQLT is an amazing tool with a host of user friendly features. This post covers three I’ve found particularly useful; how to use SQLT on a test database where it isn’t installed, how to get rid of histograms and how, when your system is large, you can get the information you need, faster.
What do you know about Oracle Database statistics gathering? What would you like to know? There is a section in the Database Performance Tuning Guide, but how many people take the time to read it? And, once you know what the various procedures are and what they do, how do you decide which ones to use and when? I’ve seen a lot of tuning problems that are statistics related, and I’d like to explore the area more thoroughly, so I’m asking for your help.
When there’s a major change in the performance of your database the culprit can usually be found by looking at any changes made around the time that performance degraded, but what if nothing has changed? What do you do then? There are lots of options, but only one that will turn you into a hero!