• Data Warehouse Service

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  1. Help Center
  2. Data Warehouse Service
  3. Developer Guide
  4. Setting Configuration Parameters
  5. Appendix B: GUC Parameter Description
  6. Resource Consumption
  7. Asynchronous I/O Operations

Asynchronous I/O Operations

enable_adio_debug

Parameter description: This parameter allows the O&M personnel to generate some ADIO logs to locate ADIO issues. This parameter is used only for developers. Common users are not advised to use it.

This parameter is a SUSET parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

  • on/true indicates the log switch is enabled.
  • off/false indicates the log switch is disabled.

Default valueoff. This log switch is disabled.

enable_fast_allocate

Parameter description: Quick allocation switch of the disk space

This parameter is a SUSET parameter. Set it based on instructions provided in Table 1. This switch can be enabled only in the XFS file system.

Value range: Boolean

  • on/true indicates that the function is enabled.
  • off/false indicates that the function is disabled.

Default valueoff. This function is disabled.

prefetch_quantity

Parameter description: Describes the amount of the I/O that the row storage prefetches using the ADIO.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: An integer. The value range is from 1 MB to 1024 MB and the unit is KB.

Default value: 32MB

backwrite_quantity

Parameter description: Describes the amount of I/O that the row storage writes using the ADIO.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: An integer. The value range is from 1 MB to 1024 MB and the unit is KB.

Default value: 8MB

cstore_prefetch_quantity

Parameter description: Describes the amount of I/O that the column storage prefetches using the ADIO.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: An integer. The value range is from 1024 to 1048576 and the unit is KB.

Default value: 32MB

cstore_backwrite_quantity

Parameter description: Describes the amount of I/O that the column storage writes using the ADIO.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

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: Maximum amount of buffer I/O that the column storage writes in the database using the ADIO.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: An integer. The value range is from 4096 to INT_MAX/2 and the unit is KB.

Default value2GB

fast_extend_file_size

Parameter description: Disk size that the row storage pre-scales using the ADIO.

This parameter is a SUSET parameter. Set it based on instructions provided in Table 1.

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: 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.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: An integer ranging from 0 to 1000

Default value1