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Re: Explain the order of query
Posted by: Rick James
Date: March 19, 2012 10:38PM

If there are no subqueries or UNIONs, the tables listed in EXPLAIN are accessed in the order presented. First the execution will go into/through the first table (or its index). From there, it will reach into the next table ("Nested Loop Join"). Etc.

With subqueries, there is some jumping around to the <derived> subquery.

UNION show each of the SELECTs in the UNION, plus something like <UNION 2,3> to say that it is combining the results.

Does that answer you question? If not, provide a concrete example to discuss.

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