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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:

Parameter Name

Type

Default Value

Min

Max

temp_file_max_size_in_pages

int

-1

   

temp_volume_path

string

NULL

   

unfill_factor

float

0.1

0.1 0.3

volume_extension_path

string

NULL

   

dont_reuse_heap_file

bool

no

   
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.

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

dont_reuse_heap_file is a parameter that configures not to reallocate the empty space created by deleting tables. If this parameter is configured to 0, the heap file is reallocated; if it is configured to 1, the heap file is not reallocated. The default value is 0.