• Venkata Sidagam's avatar
    Bug #12876932 - INCORRECT SELECT RESULT ON FEDERATED TABLE · aef1982b
    Venkata Sidagam authored
    Problem description:
    Table 't' created with two colums having compound index on both the 
    columns under innodb/myisam engine at remote machine. In the local 
    machine same table is created undet the federated engine.
    A select having where clause with along 'AND' operation gives wrong 
    results on local machine.
    
    Analysis: 
    The given query at federated engine is wrongly transformed by 
    federated::create_where_from_key() function and the same was sent to 
    the remote machine. Hence the local machine is showing wrong results.
    
    Given query "select c1 from t where c1 <= 2 and c2 = 1;"
    Query transformed, after ha_federated::create_where_from_key() function is:
    SELECT `c1`, `c2` FROM `t` WHERE  (`c1` IS NOT NULL ) AND 
    ( (`c1` >= 2)  AND  (`c2` <= 1) ) and the same sent to real_query().
    In the above the '<=' and '=' conditions were transformed to '>=' and 
    '<=' respectively.
    
    ha_federated::create_where_from_key() function behaving as below:
    The key_range is having both the start_key and end_key. The start_key 
    is used to get "(`c1` IS NOT NULL )" part of the where clause, this 
    transformation is correct. The end_key is used to get "( (`c1` >= 2) 
    AND  (`c2` <= 1) )", which is wrong, here the given conditions('<=' and '=') 
    are changed as wrong conditions('>=' and '<=').
    The end_key is having {key = 0x39fa6d0 "", length = 10, keypart_map = 3, 
    flag = HA_READ_AFTER_KEY}
    
    The store_length is having value '5'. Based on store_length and length 
    values the condition values is applied in HA_READ_AFTER_KEY switch case.
    The switch case 'HA_READ_AFTER_KEY' is applicable to only the last part of 
    the end_key and for previous parts it is going to 'HA_READ_KEY_OR_NEXT' case, 
    here the '>=' is getting added as a condition instead of '<='.
    
    Fix:
    Updated the 'if' condition in 'HA_READ_AFTER_KEY' case to affect for all 
    parts of the end_key. i.e 'i > 0' will used for end_key, Hence added it in 
    the if condition.
    
    
    mysql-test/suite/federated/federated.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_archive.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_bug_13118.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_bug_25714.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_bug_35333.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_debug.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_innodb.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_server.test:
      modified the federated.inc file location
    mysql-test/suite/federated/federated_transactions.test:
      modified the federated.inc file location
    mysql-test/suite/federated/include/federated.inc:
      moved the file from federated suite to federated/include folder
    mysql-test/suite/federated/include/federated_cleanup.inc:
      moved the file from federated suite to federated/include folder
    mysql-test/suite/federated/include/have_federated_db.inc:
      moved the file from federated suite to federated/include folder
    storage/federated/ha_federated.cc:
      updated the 'if condition' in ha_federated::create_where_from_key() 
      function.
    aef1982b
federated_bug_35333.test 2.48 KB