How can the use of FULL OUTER JOIN affect the performance and efficiency of a MySQL query in PHP?

Using a FULL OUTER JOIN in MySQL can affect the performance and efficiency of a query because it combines the results of both LEFT and RIGHT joins, potentially resulting in a larger result set. This can lead to slower query execution times and increased resource usage. To improve performance, consider using INNER JOIN or LEFT JOIN instead of FULL OUTER JOIN if possible. 

$query = "SELECT * FROM table1 
          LEFT JOIN table2 ON table1.id = table2.id 
          WHERE table1.id IS NOT NULL 
          UNION 
          SELECT * FROM table1 
          RIGHT JOIN table2 ON table1.id = table2.id 
          WHERE table2.id IS NULL";
$result = mysqli_query($connection, $query);

Keywords

FULL OUTER JOIN performance efficiency MySQL query PHP

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