umber of records.  "capsiz"
 specifies the capacity size of using memory.  Records spilled the capacity are removed by
 the storing order.  "mode" can contain "w" of writer, "r" of reader, "c" of creating, "t" of
 truncating, "e" of no locking, and "f" of non-blocking lock.  The default mode is relevant
 to "wc".  "opts" can contains "l" of large option, "d" of Deflate option, "b" of BZIP2
 option, and "t" of TCBS option.  "idx" specifies the column name of an index and its type
 separated by ":".  For exam