CBO costing
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Resp: you might have spotted it “here and there” in the 10053 trace file.It may turn out important if, for example, all of sudden your SQL similar to the one below starts running in parallel (of what you may not be aware straight away), visibly slower – and most of all wasting I/O and CPU…
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Cartesian Join & Hash Join – Bonnie and Clyde “This movie is based on true story” Some time ago, I was approached to provide a solution to a performance issue.To illustrate this case, I will later simulate the scenario highlighting the critical aspects and providing a detailed explanation of the underlying causes.For now, let me…
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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,…