Following a Plan

The execution plan (often called the query execution plan or the explain plan) contains the individual steps a database goes through to execute a SQL statement. For example, execution plans provide information on which indexes are used, in which order access to the various tables occurs, and what algorithms are used for joins, sorting, and grouping operations.

The execution plan roughly corresponds to bytecode in scripting languages like Perl or Python – it is used internally to execute SQL statements. Creating an execution plan is sometimes also known as a compiling. However, this is more commonly referred to as the prepare phase ....

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