19.3 Determining the maximum number of files (pdfmkfs -l command)
To specify the maximum number of work table files to be created in a HiRDB file system area, use the pdfmkfs command's -l option.
You can use the following formula to determine the maximum number of work table files that need to be created in a HiRDB file system area:
- Formula
Maximum number of files = MAX(a, b) c + 20 + 2* |
- a: Number of work table files to be used by one SQL statement
- Calculate the number of work table files to be used by each SQL statement and specify the largest such value for a in the formula; see (1) as follows.
- b: Number of work table files to be used by an ASSIGN LIST statement
- Calculate the number of work table files to be used by each ASSIGN LIST statement and specify the largest such value for b in the formula; see (2) as follows.
- c: Value of the pd_max_users operand + value of the pd_max_reflect_process_count operand
- However, when multiple front-end servers are being used, the back-end servers are (value of the pd_max_bes_process operand + value of the pd_max_reflect_process_count operand).
- * Add this value if you execute an SQL statement that uses a work table file concurrently with a utility that also uses a work table file (database load utility or database reorganization utility).
- Organization of this section
- (1) Obtaining the number of work table files to be used by one SQL statement
- (2) Obtaining the number of work table files to be used by an ASSIGN LIST statement
- (3) Note
(1) Obtaining the number of work table files to be used by one SQL statement
To obtain the number of work table files to be used by one SQL statement, use the following formula:
- Formula
Number of work table files to be used by one SQL statement = maximum number of column information work tables + maximum number of location information work tables |
- For details about the maximum numbers of column information work tables and location information work tables, see 19.2.1 Size of a work table file used by an SQL statement.
(2) Obtaining the number of work table files to be used by an ASSIGN LIST statement
To obtain the number of work table files to be used by an ASSIGN LIST statement, use the following formula:
- Formula
Number of work table files to be used by an ASSIGN LIST statement = number of predicates in the search condition of ASSIGN LIST statement 2 |
(3) Note
When specifying multiple HiRDB file system areas to create work table files, note the following:
- If the value obtained is greater than 4096, specify a value of 4096 in the -l option.