Is there a reason MySQL doesn't support FULL OUTER JOINS?

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Is there a reason MySQL doesn't support FULL OUTER JOINS? I've tried full outer join syntax in mysql many times and it never worked, just found out its not supported by mysql so just curious as to why?

mysql sql
6 Answers

From High Performance MySQL:

At the moment, MySQL’s join execution strategy is simple: it treats every join as a nested-loop join. A FULL OUTER JOIN can’t be executed with nested loops and backtracking as soon as a table with no matching rows is found, because it might begin with a table that has no matching rows.This explains why MySQL doesn’t support FULL OUTER JOIN

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