• unknown's avatar
    Fix bug lp:869036 · 42221aba
    unknown authored
    Apart from the fix, the patch also adds few more unrelated test
    cases for partial matching, and fixes few typos.
    
    Analysis:
    This bug uncovered that partial matching via rowid intersection
    didn't handle the case when:
    - the left IN argument has some NULLs,
    - there are no non-null value matches, and there is no non-null
      column,
    - the subquery columns that are not covered with the NULLs in
      the left IN argument contain at least one row, such that it
      has NULL values in all columns where the left IN operand has
      no NULLs.
    In this case there is a partial match.
    
    In addition the analysis of the related code uncovered incorrect
    handling of few other related cases.
    
    Solution:
    The solution for the bug is to check if there exists a row with
    NULLs in all columns other than the ones having NULL in the
    let IN operand.
    
    The check is implemented via checking whether the bitmaps that
    store NULL information in class Ordered_key have a non-empty
    intersection for the relevant columns.
    
    The intersection itself is implemented via the function
    bitmap_exists_intersection() in my_bitmap.c.
    42221aba
item_subselect.cc 167 KB