Explain plans

This is another one of those sections that will be a little more technical than most; however, as I have said, reading an explain plan is generally not done by enough people during the development of a query. There is almost always more than one way to ask a question with a query. Understanding how the database engine is reacting to the question is key for a good performance as well as consistently well-written queries.

Understanding the output from the EXPLAIN command is more than simply understanding the order in which the query was processed. It is about understanding the kinds of operators that were used to build the query and how the data was accessed. Through a combination of SVL_query_summary and SVL_query_report data, you ...

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