Help Center/ GaussDB/ Developer Guide(Centralized_3.x)/ Configuring Running Parameters/ GUC Parameters/ Resource Consumption/ Asynchronous I/O
Updated on 2024-05-07 GMT+08:00
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Asynchronous I/O

checkpoint_flush_after

Parameter description: Specifies the threshold for the number of pages flushed by the checkpointer thread. If the threshold is exceeded, the operating system is instructed to flush the pages cached in the operating system asynchronously. In GaussDB, the disk page size is 8 KB.

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

Value range: an integer ranging from 0 to 256. 0 indicates that the asynchronous flush function is disabled. For example, if the value is 32, the checkpointer thread continuously writes 32 disk pages (that is, 32 x 8 = 256 KB) before asynchronous flush.

Default value: 256 KB

bgwriter_flush_after

Parameter description: Specifies the threshold for the number of pages flushed by the background writer thread. If the threshold is exceeded, the background writer thread instructs the operating system to asynchronously flush the pages cached in the operating system to disks. In GaussDB, the disk page size is 8 KB.

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

Value range: an integer ranging from 0 to 256. 0 indicates that the asynchronous flush function is disabled. The size of a single page is 8 KB. For example, if the value is 64, the background writer thread continuously writes 64 disk pages (that is, 64 x 8 = 512 KB) before asynchronous flush.

Default value: 512 KB (64 pages)

backend_flush_after

Parameter description: Specifies the threshold for the number of pages flushed by the backend thread. If the number of pages exceeds the threshold, the backend thread instructs the OS to asynchronously flush the pages cached in the OS to disks. In GaussDB, the disk page size is 8 KB.

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

Value range: an integer ranging from 0 to 256. 0 indicates that the asynchronous flush function is disabled. The size of a single page is 8 KB. For example, if the value is 64, the backend thread continuously writes 64 disk pages (that is, 64 x 8 = 512 KB) before asynchronous flush.

Default value: 0

Parent topic: Resource Consumption