Disk-Related Parameters

The following are disk-related parameters for defining database volumes and saving files. The type and value range for each parameter are as follows:

temp_file_max_size_in_pages

temp_file_max_size_in_pages is a parameter that configures the maximum number of pages to store temporary volumes in the disk, which are used for the execution of complex queries or sorting. The default value is -1. If this parameter is configured to the default value, unlimited number of temporary volumes are created and stored in the directory specified by the temp_volume_path parameter. If it is configured to 0, the administrator must create temporary volumes manually by using the cubrid addvoldb utility because temporary volumes are not created automatically.

temp_volume_path

temp_volume_path is a parameter that specifies the directory in which to create temporary volumes used for the execution of complex queries or sorting. The default value is the volume location configured during the database creation.

volume_extension_path

volume_extension_path is a parameter that specifies the directory in which to create extra volumes if cubrid addvoldb is used without -F option that specifies the extra volume path. The default value is the volume location configured during the database creation.

unfill_factor

unfill_factor is a parameter that defines the rate of disk space to be allocated in a heap page for data updates. The default value is 0.1. That is, the rate of free space is configured to 10%. In principle, data in the table is inserted in physical order. However, if the size of the data increases due to updates and there is not enough space for storage in the given page, performance may degrade because updated data must be relocated to another page. To prevent such a problem, you can configure the rate of space for a heap page by using the unfill_factor parameter. The allowable maximum value is 0.3 (30%). In a database where data updates rarely occur, you can configure this parameter to 0.0 so that space will not be allocated in a heap page for data updates. If the value of the unfill_factor parameter is negative or greater than the maximum value, the default value (0.1) is used.

volume_extension_path

volume_extension_path is a parameter that specifies the directory where automatically extended volumes are to be created. The default value is the volume location configured during the database creation.

dont_reuse_heap_file

The parameter "dont_reuse_heap_file" specifies whether or not heap files, which are deleted when deleting the table (DROP TABLE), are to be reused when creating a new table (CREATE TABLE). If this parameter is set to 0, the deleted heap files can be reused; if it is set to 1, the deleted heap files are not used when creating a new table. The default value is 0.

db_volume_size

db_volume_size is a parameter that defines the following values. The default value is 512M.

• The default database volume size when cubrid createdb and cubrid addvoldb utility is used without --db-volume-size option.
• The default size of generic volume that is added automatically when database volume is full.

log_volume_size

log_volume_size is a parameter that defines the default size of log volume file when cubrid createdb utility is used without --log-volume-size option. You can set units as K, M, G and T, which stand for KB(kilobytes), MB(megabytes), GB(gigabytes) and TB(terabytes), respectively. If you omit the unit, bytes will be applied. The default value is 512M.