max table num in join

[Yoshiaki Tajika]

I'd like to join over 61 tables.

The max table num in join is defined in sql/unireg.h

----------------------
#define MAX_TABLES (sizeof(table_map)*8-3) /* Max tables in join */
#define PARAM_TABLE_BIT (((table_map) 1) << (sizeof(table_map)*8-3))
#define OUTER_REF_TABLE_BIT (((table_map) 1) << (sizeof(table_map)*8-2))
#define RAND_TABLE_BIT (((table_map) 1) << (sizeof(table_map)*8-1))
#define PSEUDO_TABLE_BITS (PARAM_TABLE_BIT | OUTER_REF_TABLE_BIT | \
RAND_TABLE_BIT)
-------------------------

The 'table_map' equals ulonglong (typedef in sql/mysql_priv,h).
So, sizeof(table_map)*8-3 = 8*8-3 = 61. This is max num to be joined.

I'd like to make it larger, How should I change these defined values?
I don't understand why it is multiplied by 8, and subtract 3, and
what relationship are there between MAX_TABLES and PARAM_TABLE_BIT,
OUTER_REF_TABLE_BIT, ... etc.

Please give me advice.