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文章列表
Reading the Plan   解读计划  (page163)     Before I dive further into capturing actual execution plan data, I want to make sure you are comfortable with reading a plan.  I’ve already discussed the importance of the PARENT_ID column in making it easier for you to break a long, complex plan down into ...
Understanding How EXPLAIN PLAN can Miss the Mark 理解解释计划怎么会错误标记     One of the most frustrating things about EXPLAIN PLAN output is that it may not always match the plan that is used when the statement is actually executed.  There are three things to keep in mind about using EXPLAIN PLAN that make ...
Chapter 6--SQL Execution Plans    SQL执行计划 6.1 Explain Plan 解释计划 Karen Morton You’ve seen quite a few execution plans in the first chapters of this book, but in this chapter I’m going to go into detail about how to produce and read plans correctly.  I’ve built the found ...
5.6 Building Logical Expresions 构建逻辑表达式 (page 140)     Once you understand the question that the statement you are writing needs to answer, you have to be able to build the SQL to provide the answer.  There are often many possible ways to express the same predicate logic.  Being a ...
Questions about Data  关于数据的问题 (page 134)     I hope at this point you agree that you do need to concern yourself with how data is stored and how it should be accessed.  Where do you find this information?  The database can give you most of the answers you need by executing a few simple queries.  O ...
5.4 Questions about the Question   关于问题的问题 (page 132)      Developing new queries is usually easier than trying to modify a query that someone else has already written.  This is because when you write a brand new query, you don’t have to worry about interpreting the meaning of someone else’s co ...
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