int DB->set_h_nelem(DB *db, u_int32_t h_nelem);
Set an estimate of the final size of the hash table.
If not set or 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 interface may be used only to configure Berkeley DB before the DB->open interface is called.
The DB->set_h_nelem function returns a non-zero error value on failure and 0 on success.
The DB->set_h_nelem function may fail and return a non-zero error for the following conditions:
Called after DB->open was called.
The DB->set_h_nelem function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB->set_h_nelem function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.
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