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  1. 02 Jun, 2010 1 commit
    • Luis Soares's avatar
      BUG#53893: RBR: nullable unique key can lead to out-of-sync slave · 8ce9f9b3
      Luis Soares authored
      When using Unique Keys with nullable parts in RBR, the slave can
      choose the wrong row to update. This happens because a table with
      an unique key containing nullable parts cannot strictly guarantee 
      uniqueness. As stated in the manual, for all engines, a UNIQUE 
      index allows multiple NULL values for columns that can contain 
      NULL.
      
      We fix this at the slave by extending the checks before assuming
      that the row found through an unique index is is the correct
      one. This means that when a record (R) is fetched from the storage
      engine and a key that is not primary (K) is used, the server does 
      the following: 
      
       - If K is unique and has no nullable parts, it returns R;
       - Otherwise, if any field in the before image that is part of K
         is null do an index scan;
       - If there is no NULL field in the BI part of K, then return R.
      
      A side change: renamed the existing test case file and added a
      test case covering the changes in this patch.
      8ce9f9b3
  2. 27 Sep, 2009 1 commit
    • Luis Soares's avatar
      BUG#47312: RBR: Disabling key on slave breaks replication: · 80f96fae
      Luis Soares authored
      HA_ERR_WRONG_INDEX
            
      In RBR, disabling keys on slave table will break replication when
      updating or deleting a record. When the slave thread tries to
      find the row, by searching in the storage engine, it checks
      whether the table has a key or not. If it has one, then the slave
      thread uses it to search the record.
            
      Nonetheless, the slave only checks whether the key exists or not,
      it does not verify if it is active. Should the key be
      disabled (eg, DBA has issued an ALTER TABLE ... DISABLE KEYS)
      then it will result in error: HA_ERR_WRONG_INDEX.
            
      This patch addresses this issue by making the slave thread also
      check whether the key is active or not before actually using it.
      80f96fae