Documentation
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Overview ¶
Package bloom is a token bloom filter for full-text pruning: a compact, approximate set of the terms present in a column block (e.g. every token across a log part's bodies). A query token that tests **absent** is definitely not in the block, so the reader skips the whole block; a token that tests present may be a false positive, so the engine re-checks the exact predicate per row. The filter never reports a false negative — a token that was [Filter.Add]ed always [Filter.Test]s present — which is what makes block-skipping safe.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
func Tokenize ¶
Tokenize splits s into lowercased tokens — maximal runs of ASCII letters/digits — appending each to dst and returning the extended slice. Non-alphanumeric bytes are separators. Each token is a freshly allocated, lowercased copy (it does not alias s). It is the tokenization used both to fill a body bloom at flush and to derive a query's required tokens, so the two agree.
Types ¶
type Filter ¶
type Filter struct {
// contains filtered or unexported fields
}
Filter is a bit-array bloom filter with k hash probes derived from one 128-bit hash by double-hashing (Kirsch–Mitzenmacher). The zero value is not usable; build one with New.
func Decode ¶
Decode parses a filter encoded by Filter.Encode, returning it and the number of bytes consumed. It is fully bounds-checked and verifies the trailing CRC.
func New ¶
New returns a filter sized for n expected items at false-positive rate p (0 < p < 1), using the standard m = -n·ln p / (ln2)² and k = (m/n)·ln2, with m rounded up to a multiple of 64 and both m and k clamped to at least their minimums.
Source Files