The following formula is used to obtain the total size of all system log files.

Formula

Total size of all system log files (bytes) = (a c 3)* b

a: Amount of system log information to be output

For the procedure for obtaining this value, see (2), as follows.

b: System log file record length that is specified in the pd_log_rec_leng operand

c: Use one of the following values:

pd_log_rec_leng = 1024: 1000
pd_log_rec_leng = 2048: 2000
pd_log_rec_leng = 4096: 4000

Notes

• Because there may be unused space in system log files, it is recommended that the allocation size be at least 1.2 times the value obtained.
• Because extension information is added when the inner replica facility is used, allocate 1.1 times the value obtained.
• The value obtained is converted to a size per unit of time, and then an estimate is made of the size of one system log file and the number of system log files. The unload intervals for the system log files must be taken into account.

^* This is the formula for obtaining the total number of system log file records.

The following formula is used to obtain the amount of system log information that will be output.

Formula

Amount of system log information to be output (bytes) = {b + e + b(a - 256) 256 + d} + c For a recovery-unnecessary front-end server only, add: + f

refers to the total for each transaction. However, if an executing transaction satisfies all the following conditions, that part will not be output to the system log:

• The transaction is performing a retrieval, and it ends with the COMMIT statement.
• The server that is executing the transaction is a Single Server, a dictionary server, or a back-end server.

a: Value of the pd_log_max_data_size operand

b: 1328 + amount of system log information that is output depending on the database manipulation

Note that the value is 0 for a recovery-unnecessary front-end server.

This is the total amount of system log information that is obtained for each transaction, as explained in 18.1.2 Amount of system log information output during table definition through 18.1.5 Amount of system log information output during database creation by a utility.

c: Amount of system log information that is output depending on the SQL manipulation

See 18.1.6 Amount of system log information that is output depending on the SQL manipulation.

d: Value calculated using the following formula for each server type

• For HiRDB/Single Server
  2 pd_log_rec_leng operand value
  
• For HiRDB/Parallel Server
  For a front-end server
  

  Execution of UAP using the HiRDB library to implement a connection method that supports multi-threading and complies with X/Open, and use of the transaction transfer facility	Use of recovery-unnecessary front-end server	Formula
  Used	Not used (cannot be used)	(1328 pd_log_rec_leng operand value + 3) pd_log_rec_leng operand value
  Not used	Used	0
  Not used	Not used	2 pd_log_rec_leng operand value

  For a back-end server or a dictionary server
  

  The system includes a front-end server that uses a recovery-unnecessary front-end server	pd_rpl_reflect_mode operand specification value	Formula
  Yes	uap	2 pd_log_rec_leng operand value + 128 (all BESs + all FESs) pd_log_rec_leng operand value pd_log_rec_leng operand value
  	server
  No	uap
  	server	2 pd_log_rec_leng operand value

e:

• For a HiRDB/Parallel Server
  For a front-end server: 56 total number of back-end servers
  Other than a front-end server: 0
  
• For a HiRDB/Single Server: 0

f: 10 value of pd_log_rec_leng

Notes

The system log is output when any of the following operations takes place:

• Table definition
• Index definition
• Table data updating
• Database creation by a utility

If rollback occurs while the database is being updated during any of these operations, the amount of system log information applicable to the part of the database updated up to that point is added and output; this must be taken into account in estimating the size of system log information.