#include <db.h> int DB_ENV->cdsgroup_begin(DB_ENV *dbenv, DB_TXN **tid);
         The DB_ENV->cdsgroup_begin() method allocates a locker ID in an
         environment configured for Berkeley DB Concurrent Data Store
         applications.  It copies a pointer to a 
         DB_TXN  that uniquely identifies
         the locker ID into the memory to which tid refers.  
         Calling the 
         DB_TXN->commit()  method will
         discard the allocated locker ID.
    
See Berkeley DB Concurrent Data Store applications for more information about when this is required.
         The DB_ENV->cdsgroup_begin() method may be called at any time during
         the life of the application.
    
         The DB_ENV->cdsgroup_begin() 
            
                  method returns a non-zero error value on failure and 0 on success.
            
            
        
    
                     The DB_ENV->cdsgroup_begin() 
            
                 method may fail and return one of the following non-zero errors: