This section explains the recommended values of the operands for various types of foreign servers.

The values in the Hub optimization information definition sample file are the same as the values recommended here. Therefore, use the values in the Hub optimization information definition sample file without any modification. For the storage location of the Hub optimization information definition sample file, see the HiRDB External Data Access Version 7 Description and User's Guide.

Operand name	HiRDB Version 6 or later	HiRDB Version 5.0	XDM/RD E2	ORACLE	DB2
pd_hub_opt_on_cnd	1	1	1	2	1
pd_hub_opt_joined_table	1	3	1	2	1
pd_hub_opt_set_func	1	3	3	1	4
pd_hub_opt_case	1	1	1	2	1
pd_hub_opt_like1	1	1	4	4	4
pd_hub_opt_grouping	1	1	4	3	4
pd_hub_opt_data_len2	255	255	255	255	248
pd_hub_opt_abs	1	1	1	3	2
pd_hub_opt_date	1	1	1	3	1
pd_hub_opt_time	1	1	1	2	1
pd_hub_opt_digits	1	1	1	2	1
pd_hub_opt_length	1	1	3	7	3
pd_hub_opt_lower_upper_type	1	1	1	6	7
pd_hub_opt_mod_div_type	1	1	2	1	3
pd_hub_opt_substr	1	1	3	2	2
pd_hub_opt_num	1	1	1	2	1
pd_hub_opt_datetime	1	1	1	2	1
pd_hub_opt_datetime_op	1	1	1	5	4
pd_hub_opt_trailing_spc	1	1	1	1	2
pd_hub_opt_nullable	1	1	1	2	1
pd_hub_opt_use_zero_string	1	1	1	2	1
pd_hub_opt_nchar3	1	1	2	2	1
pd_hub_opt_nest_scalar	0	0	0	0	100
pd_hub_opt_float	2	2	2	2	2
pd_hub_opt_table_num	64	64	64	64	15
pd_hub_opt_time_24hour	1	1	1	1	2

¹ If a LIKE predicate, NOT LIKE predicate, XLIKE predicate, or NOT XLIKE predicate for the character string-type, variable-size character string-type, mixed character string-type, or variable-size mixed character string-type data contains two-byte special characters, or if a LIKE predicate, NOT LIKE predicate, XLIKE predicate, or NOT XLIKE predicate for the national character string-type or variable-size national character string-type data contains one-byte special characters, do not execute these predicates using the foreign server.

² Although the maximum size of the character string type that can be defined in DB2 is 255 bytes, the maximum size of a character string-type constant that can be used is 248. If you need to use a character string-type constant that is 249 bytes or longer, use a concatenation operation.

³ If the national character-type character code set of the foreign server is not fixed to 2 bytes, specify 2.