Shulou(Shulou.com)06/01 Report--

1.sql execution process

1 > parsing (determine whether the object exists, whether it has permission to query, semantic parsing, check whether there is the same SQL in the cache, etc.)

2 > Optimization (CBO determines the optimization mode, access path and connection order. In the process, various ways of resource consumption are estimated through many comprehensive factors, and the minimum consumption is selected as the best)

3 > generate QEP (Query Execution Plan: query execution plan)

4 > execute QEP and return the result

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