• Igor Babaev's avatar
    Fixed bug mdev-4894. · 6dd9f049
    Igor Babaev authored
    This a an old legacy performance bug.
    When a very selective range scan existed for the second table in a join,
    and, at the same time, there was another range condition depending on the
    fields of the first table, the optimizer chose a plan with
    'Range checked for each record'. This plan was extremely inefficient in
    comparison with the regular selective range scan.
    As a matter of fact the range scan chosen for each record was the same as
    that selective range scan. 
    
    Changed the test case for bug 24776 to preserve the old output for explain.
     
    6dd9f049
sql_select.cc 569 KB