• unknown's avatar
    Fix for BUG#16710. · bb839d3a
    unknown authored
    The bug was due to a missed case in the detection of whether an index
    can be used for loose scan. More precisely, the range optimizer chose
    to use loose index scan for queries for which the condition(s) over
    an index key part could not be pushed to the index together with the
    loose scan.
    
    As a result, loose index scan was selecting the first row in the
    index with a given GROUP BY prefix, and was applying the WHERE
    clause after that, while it should have inspected all rows with
    the given prefix, and apply the WHERE clause to all of them.
    
    The fix detects and skips such cases.
    
    
    mysql-test/r/group_min_max.result:
      Added test for BUG#16710.
    mysql-test/t/group_min_max.test:
      Added test for BUG#16710.
    sql/item.cc:
      Added new method [Item | Item_field]::find_item_in_field_list_processor.
    sql/item.h:
      Added new method [Item | Item_field]::find_item_in_field_list_processor.
    sql/opt_range.cc:
      Handle the case when there is no MIN/MAX aggregate function, and a
      keypart of the index being considered, that is after the GROUP BY
      prefix, is used in the WHERE clause and the condition where it is
      used cannot be pushed to the index.
      If this is the case, we rule out this index.
    bb839d3a
group_min_max.result 76.7 KB