HdrHistogram Redis Type and corresponding commands based on the HdrHistogram_C by Michael Barker.
This Redis Module is Work in Progress / Prototype. Not all documented commands are implemented yet. The module is not used in production and currently under development to serve as a potential replacement for our current Elasticsearch based storage.
- Fix rdb unserialize read problem, probably bug in code.
- Implement
HdrTypeAofRewritecorrectly - Implement missing commands.
- Add installation documentation
HDR.NEW key min max sf
Create a new HDR histogram with given key as name, a range between min and max with significant figures 1, 2 or 3.
HDR.ADD key value [value ...]
Record multiple different values into the histogram at given key.
HDR.ADDC key value count
Record multiple counts of the same value into the histogram at given key.
HDR.IMPORT key lo hi sf bucket_count [bucket_count ...]
Import a serialized histogram from outside of Redis into the key, either creating a new histogram with lo, hi, sf or merging into an existing one. This function is useful if you are collecting the histogram data outside of Redis and import it for storage.
HDR.MERGE dest source [source ...]
Merge one or more histograms together into a new or existing destination key. If the destination does not exist, lo, hi and sf from the first histogram in the source list are used for the initialization.
HDR.PERCENTILE key percentile [percentile ...]
Get the value of a queried percentile (or more than one) for the given histogram. The percentile values are doubles in the range from 0.0 to 100.0 This command allows you answer the question which latency is the 50, 95, 99s or any other percentile?
HDR.CDF key value [value ...]
Calculate the cummulative distribution function's value for given bucket values. This command allows you to answer the question at which percentile is the latency $x?
HDR.GET key [key ...]
Return histogram as a Redis list with pairs of values for bucket and number of entries. Merge histograms if multiple are queried.
HDR.GETB key
Return histogram as a list of buckets, starting with 3 metadata values for hi, lo and sf.