Functions to create and manipulate probabilistic cardinality counters.
Namespace: | GLOBAL |
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Source File: | /scripts/base/bif/cardinality-counter.bif.bro |
hll_cardinality_add: function | Adds an element to a HyperLogLog cardinality counter. |
hll_cardinality_copy: function | Copy a HLL cardinality counter. |
hll_cardinality_estimate: function | Estimate the current cardinality of an HLL cardinality counter. |
hll_cardinality_init: function | Initializes a probabilistic cardinality counter that uses the HyperLogLog algorithm. |
hll_cardinality_merge_into: function | Merges a HLL cardinality counter into another. |
Type : | function (handle: opaque of cardinality, elem: any) : bool |
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Adds an element to a HyperLogLog cardinality counter.
Handle : | the HLL handle. |
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Elem : | the element to add. |
Returns : | true on success. |
See also: hll_cardinality_estimate, hll_cardinality_merge_into, hll_cardinality_init, hll_cardinality_copy
Type : | function (handle: opaque of cardinality) : opaque of cardinality |
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Copy a HLL cardinality counter.
Handle : | cardinality counter to copy. |
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Returns : | copy of handle. |
See also: hll_cardinality_estimate, hll_cardinality_merge_into, hll_cardinality_add, hll_cardinality_init
Type : | function (handle: opaque of cardinality) : double |
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Estimate the current cardinality of an HLL cardinality counter.
Handle : | the HLL handle. |
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Returns : | the cardinality estimate. Returns -1.0 if the counter is empty. |
See also: hll_cardinality_merge_into, hll_cardinality_add, hll_cardinality_init, hll_cardinality_copy
Type : | function (err: double, confidence: double) : opaque of cardinality |
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Initializes a probabilistic cardinality counter that uses the HyperLogLog algorithm.
Err : | the desired error rate (e.g. 0.01). |
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Confidence : | the desired confidence for the error rate (e.g., 0.95). |
Returns : | a HLL cardinality handle. |
See also: hll_cardinality_estimate, hll_cardinality_merge_into, hll_cardinality_add, hll_cardinality_copy
Type : | function (handle1: opaque of cardinality, handle2: opaque of cardinality) : bool |
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Merges a HLL cardinality counter into another.
Note
The same restrictions as for Bloom filter merging apply, see bloomfilter_merge.
Handle1 : | the first HLL handle, which will contain the merged result. |
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Handle2 : | the second HLL handle, which will be merged into the first. |
Returns : | true on success. |
See also: hll_cardinality_estimate, hll_cardinality_add, hll_cardinality_init, hll_cardinality_copy