18.3 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) x 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
However, when multiple front-end servers are being used, the back-end servers are value of the pd_max_bes_process 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 18.2.1 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 x 2

(3) Note

When specifying multiple HiRDB file system areas to create work table files, note the following: