6.24.2 Points to consider when specifying the number of processing real threads for a group

(1) Points to consider when specifying the maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group

Consider the following when you use the client-group facility and you specify a maximum number of processing real threads and a guaranteed minimum number of processing real threads usable by a group:

• What would be the number of processing real threads on the HADB server?

  Evaluate the value of the adb_sys_rthd_num operand in the server definition. For details about the adb_sys_rthd_num operand in the server definition, see the description of the adb_sys_rthd_num operand in 7.2.2 Operands related to performance (set format).

• What would be the maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group?

  You can use the adbcltgrp operand in the server definition to specify the maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group. For details about the adbcltgrp operand in the server definition, see 7.2.12 Operands and options related to the client-group facility (command format).

• How many processing real threads would be needed for HADB clients and commands that belong to no group?

  The number of processing real threads usable by HADB clients and commands that belong to no group is determined by the number of processing real threads on the HADB server and by the maximum number of processing real threads and the guaranteed minimum number of processing real threads that can be used by each group.

  The number of processing real threads usable by HADB clients and commands that belong to no group is within the range of the freely usable number of processing real threads. The number of freely usable processing real threads is the number of processing real threads on the HADB server minus the guaranteed minimum number of processing real threads that can be used by each group.

  Taking this relationship into account, specify the appropriate maximum number of processing real threads and guaranteed minimum number of processing real threads usable by a group.

The following figure provides an overview of the range of processing real threads that are used when the client-group facility is used.

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(2) How to determine the numbers of processing real threads when the client-group facility is used

This subsection explains how to determine the numbers of processing real threads when the client-group facility is used.

■ How to determine the maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group

The maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group are determined by the values of the adbcltgrp and adb_sys_rthd_num operands in the server definition. The HADB clients and commands that belong to a group can use processing real threads within the range of the maximum number of processing real threads and the guaranteed minimum number of processing real threads specified for the group. The following table explains the maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group.

Table 6‒30: Maximum number of processing real threads and the guaranteed minimum number of processing real threads usable by a group

No.	Type of processing real thread count	Value
1	Maximum number of processing real threads#	The value is determined by the following formula:
2	Guaranteed minimum number of processing real threads that can be used	The value is as follows: Value of the -e option in the adbcltgrp operand in the server definition for the target group

#

The following cannot be executed unless the minimum number of processing real threads required can be allocated. Therefore, the maximum number of processing real threads must be adjusted so that a number of processing real threads at least equal to the minimum number of processing real threads required is allocated. If a number of processing real threads at least equal to the minimum number of processing real threads required cannot be allocated, execution of the following commands might result in an error:

• adbimport command

• adbidxrebuild command

• adbgetcst command

• adbexport command

• adbmergechunk command

• adbarchivechunk command

• adbunarchivechunk command

• adbreorgsystemdata command

For details about the minimum number of processing real threads required by each command, see Table 6‒28: Operands and command options for specifying the number of processing real threads to be used for command execution in (2) Operands and command options for specifying the number of processing real threads to be used for command execution under 6.23.2 Points to consider about the number of processing real threads to be used during command execution.

■ How to determine the number of freely usable processing real threads

The freely usable processing real threads are available to all HADB clients and commands regardless of whether they belong to a group. Use the following formula to determine the number of freely usable processing real threads.

Formula

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(3) Relationships among processing real thread counts when the client-group facility is used

The following figure shows the relationships among the different types of processing real thread counts explained in (2) How to determine the numbers of processing real threads when the client-group facility is used when the client-group facility is used.

Explanation:

• The guaranteed minimum number of processing real threads that can be used by the client group (15) and the guaranteed minimum number of processing real threads that can be used by the command group (10) are allocated from the number of processing real threads on the HADB server (80). Therefore, the remaining processing real threads (55) belong to the freely usable processing real threads. The freely usable processing real threads are available to all HADB clients and commands regardless of whether they belong to a group.

• Of the freely usable processing real threads (55), each group can use up to its maximum number of processing real threads that can be used minus its guaranteed minimum number of processing real threads that can be used. In this example, the client group can use up to its local group's maximum number of processing real threads that can be used (35) minus its guaranteed minimum number of processing real threads that can be used (15) as freely usable processing real threads (20). The command group can use up to its maximum number of processing real threads that can be used (25) minus its guaranteed minimum number of processing real threads that can be used (10) as freely usable processing real threads (15).

Note

Depending on the sum of the maximum numbers of processing real threads that can be used by all groups, a portion of the freely usable processing real threads might become available only to HADB clients and commands that belong to no group. The following figure shows the relationship between the number of processing real threads that are available only to HADB clients and commands that do not belong to any group, and the sum of the maximum numbers of processing real threads that can be used by all groups. This figure is based on the settings shown in Figure 6‒9: Relationships among processing real thread counts when the client-group facility is used.

Figure 6‒10: Relationship between the number of processing real threads that are available only to HADB clients and commands that belong to no group and the sum of the maximum numbers of processing real threads that can be used by all groups

Explanation:

If the sum of the maximum numbers of processing real threads that can be used by all groups is smaller than the number of processing real threads on the HADB server, some of the processing real threads will never be used by any group. These processing real threads become available only to HADB clients and commands that belong to no group.

In this example, the sum of the maximum numbers of processing real threads that can be used by all groups (60) is less than the number of processing real threads on the HADB server (80). As a result, 20 processing real threads will never be used by any group. These processing real threads (20) are made available only to HADB clients and commands that belong to no group.

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