Exadata
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While preparing the series of posts about Clustering Factor (aka CLUF in 10053 traces) I came across an interesting caveat which I decided to explore.I will make an attempt to explain its matter, although I encourage you to reach out to the part3 of the mentioned series and navigate to “Quantifying physical reads for low CLUF” and…
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One day, while browsing publicly available resources (blogs, white papers), I realized there’s a lack of easily accessible information on the following topic: How to map the cost-based optimizer (CBO) formulas and numbers to the SQL Plan for the most basic scenario — comparing index range scan access vs. full table scan. As we know,…
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Note: this is continuation of the previous post. Now, let’s finally simulate my problem. To do that, I will force reading the table into the SGA.To remain fair, I won’t cache it entirely.Why am I considering it a “fair” approach?It’s hard to expect, after having executed your query that the entire large table, say 200GB…
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This post contains 3 parts. Recently I witnessed an interesting case which added a headache to the application owners and the business.Namely, one of the important reports which used to run smoothly all of sudden stopped behaving.Talking numbers, something what people used to get within some seconds (up to 8) unexpectedly took close to 2…