• igor@olga.mysql.com's avatar
    Fixed bug #25602. A query with DISTINCT in the select list to which · 59b9077c
    igor@olga.mysql.com authored
    the loose scan optimization for grouping queries was applied returned 
    a wrong result set when the query was used with the SQL_BIG_RESULT
    option.
    
    The SQL_BIG_RESULT option forces to use sorting algorithm for grouping
    queries instead of employing a suitable index. The current loose scan
    optimization is applied only for one table queries when the suitable
    index is covering. It does not make sense to use sort algorithm in this
    case. However the create_sort_index function does not take into account
    the possible choice of the loose scan to implement the DISTINCT operator
    which makes sorting unnecessary. Moreover the current implementation of
    the loose scan for queries with distinct assumes that sorting will
    never happen. Thus in this case create_sort_index should not call
    the function filesort.
    59b9077c
sql_select.cc 489 KB