HyperLogLog

hll_default_log2m

Parameter description: Specifies the number of buckets for HLL data. The number of buckets affects the precision of distinct values calculated by HLL. The more buckets there are, the smaller the deviation is. The deviation range is as follows: [–1.04/2^log2m*1/2, +1.04/2^log2m*1/2]

Parameter type: integer

Unit: none

Value range: 10 to 16.

Default value: 14

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

Setting suggestion: Retain the default value or adjust the value based on service requirements.

hll_default_log2explicit

Parameter description: Specifies the default threshold for switching from the explicit mode to the sparse mode.

Parameter type: integer

Unit: none

Value range: 0–12 The value 0 indicates that the explicit mode is skipped. The value 1 to 12 indicates that the mode is switched when the number of distinct values reaches 2^{hll_default_log2explicit}.

Default value: 10

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

Setting suggestion: Retain the default value or adjust the value based on service requirements.

hll_default_log2sparse

Parameter description: Specifies the default threshold for switching from the sparse mode to the full mode.

Parameter type: integer

Unit: none

Value range: 0–14 The value 0 indicates that the explicit mode is skipped. The value 1 to 14 indicates that the mode is switched when the number of distinct values reaches 2^{hll_default_log2sparse}.

Default value: 12

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

Setting suggestion: Retain the default value or adjust the value based on service requirements.

hll_duplicate_check

Parameter description: Specifies whether duplicatecheck is enabled by default.

Parameter type: Boolean

Unit: none

Value range:

• 0: The function is disabled by default.
• 1: The function is enabled by default.

Default value: 0

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

Setting suggestion: Retain the default value or adjust the value based on service requirements.