Determines the best index to use for searching for a column value.
public virtual const char * GetOptimalIndex(ul_column_num cid)
cid A 1-based ordinal column number.
The name of the index or NULL if the column isn't indexed. Warning: this points to a static buffer whose contents may be changed by any subsequent UltraLite call, so you'll need to make a copy of the value if you need to keep it for a while.