#include <db_cxx.h> int Db::set_h_nelem(u_int32_t h_nelem);
Set an estimate of the final size of the hash table.
In order for the estimate to be used when creating the database, the Db::set_h_ffactor() method must also be called. If the estimate or fill factor are not set or are set too low, hash tables will still expand gracefully as keys are entered, although a slight performance degradation may be noticed.
         The Db::set_h_nelem() method configures a database, not only
         operations performed using the specified Db  
         handle.
    
         The Db::set_h_nelem() method may not be called after the 
         Db::open()  method is called. If
         the database already exists when Db::open()  
         is called, the information specified to Db::set_h_nelem() will be ignored.
    
         The Db::set_h_nelem() 
            
            
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            
        
    
                         The Db::set_h_nelem() 
            
            
                method may fail and throw a DbException 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors:
            
        
                    
If the method was called after Db::open() was called; or if an invalid flag value or parameter was specified.