8.2.5 Operands related to buffers

18) pd_sql_object_cache_size = SQL-object-buffer-size
~<unsigned integer> (kilobytes)
  • 32-bit mode: ((22-256000))
  • 64-bit mode: ((22-2000000))
Specifies in kilobytes the size of the buffer area (shared memory) in which SQL objects are to be placed.
Specification guidelines
  • SQL objects are saved in a buffer until the user's transaction has terminated. The buffer must be large enough to store the SQL objects of all transactions that will be executed concurrently.
  • If the SQL object buffer hit rate is low, the performance might decreases due to the overhead of SQL statement analysis processing.
  • SQL analysis can be reduced by saving the SQL objects of static SQLs in the buffer after transaction termination (until the buffer runs out of space) and sharing them among multiple users who execute the same UAP. To effectively utilize the buffer, allocate it so that the SQL objects of frequently-used UAPs are resident in the buffer.
  • To estimate the buffer size, first determine the buffer size needed for UAP execution from the length of the SQL objects from the SQL statements to be issued by the UAP. Then, compute the buffer size by considering the number of UAPs that will be executed concurrently and the number of concurrently executing users.
  • For details about how to estimate the length of the SQL object from a single SQL statement, see C.2 Formulas for determining size of SQL object buffer (pd_sql_object_cache_size).
Operand default
If this operand is omitted, the value specified for the same operand in the server common definition or the system common definition takes effect, in that order. If the same operand is also omitted from the server common definition and the system common definition, the following value is assumed:
  • 32-bit mode: (value of pd_max_users + n) [Figure] 22
  • 64-bit mode and recommended mode: (value of pd_max_users + n) [Figure] 40
  • 64-bit mode and 0904 compatibility mode: (value of pd_max_users + n) [Figure] 22
n: If a multiple front-end server configuration will be applied in a HiRDB parallel server configuration, 4. For others, 3.
Tuning the specified value
For details about how to tune the SQL object buffer size, see the HiRDB Version 9 System Operation Guide.
Effects on individual estimation formulas
If the value of the pd_sql_object_cache_size operand is changed, the following estimation formula is affected:
HiRDB Version 9 Installation and Design Guide:
  • Formula 1 under Formulas for the size of the shared memory used by a back-end server