ha_innobase.cc:

  Increase table comment print size to 500 bytes to be able to print more foreign key constraint infos
ha_innobase.h:
  Change max key len back to 500 bytes because MySQL interpreter cannot handle more

sql/ha_innobase.cc

@@ -3220,7 +3220,7 @@ ha_innobase::update_table_comment(
 {
 	row_prebuilt_t* prebuilt = (row_prebuilt_t*)innobase_prebuilt;
   	uint 		length 	= strlen(comment);
-  	char*		str 	= my_malloc(length + 200, MYF(0));
+  	char*		str 	= my_malloc(length + 550, MYF(0));
   	char*		pos;
 
 	if (!str) {
@@ -3239,7 +3239,7 @@ ha_innobase::update_table_comment(
 
 	/* We assume 150 bytes of space to print info */
 
-  	dict_print_info_on_foreign_keys(pos, 150, prebuilt->table);
+  	dict_print_info_on_foreign_keys(pos, 500, prebuilt->table);
   
   	return(str);
 }

sql/ha_innobase.h

@@ -100,8 +100,11 @@ class ha_innobase: public handler
 				a secondary key record must also contain the
 				primary key value:
 				max key length is therefore set to slightly
-				less than 1 / 4 of page size which is 16 kB */
-  	uint max_key_length()    const { return 3500; }
+				less than 1 / 4 of page size which is 16 kB;
+				but currently MySQL does not work with keys
+				whose size is > MAX_KEY_LENGTH */
+  	uint max_key_length() const { return((MAX_KEY_LENGTH <= 3500) ?
+					  MAX_KEY_LENGTH : 3500);}
   	bool fast_key_read()	 { return 1;}
 	key_map keys_to_use_for_scanning() { return ~(key_map) 0; }
   	bool has_transactions()  { return 1;}