Asynchronous I/O Operations¶
enable_adio_debug¶
Parameter description: Specifies whether to enable logging related to ADIO, which helps to locate ADIO-related issues. General users are not advised to set this O&M parameter.
Type: SUSET
Value range: Boolean
on or true indicates the log switch is enabled.
off or false indicates the log switch is disabled.
Default value: off
enable_fast_allocate¶
Parameter description: Specifies whether the quick allocation switch of the disk space is enabled. This switch can be enabled only in the XFS file system.
Type: SUSET
Value range: Boolean
on or true indicates that this function is enabled.
off or false indicates that the function is disabled.
Default value: off
prefetch_quantity¶
Parameter description: Specifies the number of row-store prefetches using the ADIO.
Type: USERSET
Value range: an integer ranging from 1024 to 1048576. The unit is 8 KB.
Default value: 32 MB
backwrite_quantity¶
Parameter description: Specifies the number of row-store writes using the ADIO.
Type: USERSET
Value range: an integer ranging from 1024 to 1048576. The unit is 8 KB.
Default value: 8MB
cstore_prefetch_quantity¶
Parameter description: Specifies the number of column-store prefetches using the ADIO.
Type: USERSET
Value range: an integer. The value range is from 1024 to 1048576 and the unit is KB.
Default value: 32 MB
cstore_backwrite_quantity¶
Parameter description: Specifies the number of column-store writes using the ADIO.
Type: USERSET
Value range: an integer. The value range is from 1024 to 1048576 and the unit is KB.
Default value: 8MB
cstore_backwrite_max_threshold¶
Parameter description: Specifies the maximum number of column-store writes buffered in the database using the ADIO.
Type: USERSET
Value range: an integer ranging from 4096 to INT_MAX/2, in KB
Default value: 2 GB
fast_extend_file_size¶
Parameter description: Specifies the disk size that the row-store pre-scales using the ADIO.
Type: SUSET
Value range: an integer. The value range is from 1024 to 1048576 and the unit is KB.
Default value: 8MB
effective_io_concurrency¶
Parameter description: Specifies the number of requests that can be simultaneously processed by the disk subsystem. For the RAID array, the parameter value must be the number of disk drive spindles in the array.
Type: USERSET
Value range: an integer ranging from 0 to 1000
Default value: 1
cu_preload_max_distance¶
Parameter description: Specifies the maximum number of CU groups that can be prefetched. This is supported only by clusters of version 9.1.0.100 or later.
Type: USERSET
Value range: an integer ranging from 0 to 1024. The value 0 indicates that prefetching is disabled.
Default value: 20
cu_preload_count¶
Parameter description: Specifies the maximum number of CUs to be prefetched. This parameter is supported only by clusters of version 9.1.0 or later.
Type: USERSET
Value range: an integer. The value ranges from 0 to 10000. The value 0 indicates that prefetching is disabled.
Default value: 600