RECONFIGURE-DBH-SESSION

This statement changes DBH options in the current DBH session.

Scope of validity

DBH administration

See also

• DBH administration statement RELOAD-DBH-SESSION on "RELOAD-DBH-SESSION"

• The DBH option COLUMNS on "COLUMNS"

• The DBH option CURSOR-BUFFER on "CURSOR-BUFFER"

• The DBH option SPACES on "SPACES"

• The DBH option SQL-SUPPORT on "SQL-SUPPORT"

• The DBH option SYSTEM-DATA-BUFFER on "SYSTEM-DATA-BUFFER"

• The DBH option TRANSACTION-SECURITY on "TRANSACTION-SECURITY"

• The DBH option USER-DATA-BUFFER on "USER-DATA-BUFFER"

Function

See section “Dynamic reconfiguration of the DBH session”.

You can use the RECONFIGURE-DBH-SESSION statement to change some DBH options in the current DBH session without reloading the DBH modules. The statement cannot be specified in a linked-in DBH.

RECONFIGURE-DBH-SESSION

CURSOR-BUFFER = *UNCHANGED / *STD / *PARAMETERS(...)
	*PARAMETERS(...)
		|	BUFFER-SIZE = *UNCHANGED / *STD / <integer 72..1500000>
		|	,FRAME-SIZE = *UNCHANGED / *STD / <integer 4..32>
,SYSTEM-DATA-BUFFER = *UNCHANGED / *STD / <integer 80..64000000>
,USER-DATA-BUFFER = *UNCHANGED / *STD / <integer 80..64000000>
,SQL-SUPPORT = *UNCHANGED / *STD / *PARAMETERS(...)
	*PARAMETERS(...)
		|	CURSORS = *UNCHANGED / *STD / <integer 0..262143>
		|	,PLANS = *UNCHANGED / *STD / <integer 1..999999>
,SPACES = *UNCHANGED / *STD / <integer 1..101600>
,COLUMNS = *UNCHANGED / *STD / <integer 256..1024>
,TRANSACTION-SECURITY = *UNCHANGED / *STD / *PARAMETERS(...)
	*PARAMETERS(...)
		|	MAX-ISOLATION-LEVEL = *UNCHANGED / *STD / *REPEATABLE-READ / *SERIALIZABLE

Operands

See the operand descriptions for the relevant DBH options.

When *UNCHANGED is specified, the value of the DBH option remains unchanged. When *STD is specified, the default value of the DBH option is used.

Further information

The final size of the buffer for system access data and of the buffer for user data is hardware-dependent and also dependent on the DBH option THREADS and the system threads which depend on this. The minimum value for the buffer size is 96 KB per thread. If the value specified is less than the minimum value, it is automatically increased to the minimum value provided the value specified is within the permitted range.

The total of the sizes for SYSTEM-DATA-BUFFER and USER-DATA-BUFFER may not exceed 64 000 000 KB (64 GB).

The minimum size of CURSOR-BUFFER per thread is dependent on the value of FRAME-SIZE and must in all cases be eight times the value of FRAME-SIZE. If more is specified by the user, the user specifications apply. However, these are always rounded up to a multiple of the FRAME-SIZE value.

The value for SPACES depends on the maximum number of entries which the SQL database directory may contain. When you enter a value for SPACES which is lower than the total of the spaces which currently exist, SESAM/SQL selects an appropriate value for SPACES. This is basically the same as the total number of spaces of all SQL database directories which are currently active.

When the value of the DBH option COLUMNS is increased, the maximum size of the work container should be adjusted accordingly in order to prevent resource bottlenecks in the WORK-CONTAINER.

In the case of RECONFIGURE-DBH-SESSION the DBH’s memory is restructured or recreated. This also causes the counters which the SESMON performance monitor evaluates for statistical purposes to be reset to “0”.