Granularity class

Granularity for BucketAuto

Granularity ensures that the boundaries of all buckets adhere to a specified preferred number series. Using a preferred number series provides more control on where the bucket boundaries are set among the range of values in the groupBy expression. They may also be used to help logarithmically and evenly set bucket boundaries when the range of the groupBy expression scales exponentially.

Renard Series

The Renard number series are sets of numbers derived by taking either the 5th, 10 th, 20 th, 40 th, or 80 th root of 10, then including various powers of the root that equate to values between 1.0 to 10.0 (10.3 in the case of R80).

Set granularity to R5, R10, R20, R40, or R80 to restrict bucket boundaries to values in the series. The values of the series are multiplied by a power of 10 when the groupBy values are outside of the 1.0 to 10.0 (10.3 for R80) range.

Example:

The R5 series is based off of the fifth root of 10, which is 1.58, and includes various powers of this root (rounded) until 10 is reached. The R5 series is derived as follows:

10 0/5 = 1
10 1/5 = 1.584 ~ 1.6
10 2/5 = 2.511 ~ 2.5
10 3/5 = 3.981 ~ 4.0
10 4/5 = 6.309 ~ 6.3
10 5/5 = 10

The same approach is applied to the other Renard series to offer finer granularity, i.e., more intervals between 1.0 and 10.0 (10.3 for R80).

E Series

The E number series are similar to the Renard series in that they subdivide the interval from 1.0 to 10.0 by the 6 th, 12 th, 24 th, 48 th, 96 th, or 192 nd root of ten with a particular relative error.

Set granularity to E6, E12, E24, E48, E96, or E192 to restrict bucket boundaries to values in the series. The values of the series are multiplied by a power of 10 when the groupBy values are outside of the 1.0 to 10.0 range. To learn more about the E-series and their respective relative errors, see preferred number series.

1-2-5 Series

The 1-2-5 series behaves like a three-value Renard series, if such a series existed.

Set granularity to 1-2-5 to restrict bucket boundaries to various powers of the third root of 10, rounded to one significant digit.

Example:

The following values are part of the 1-2-5 series: 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, and so on…

Powers of Two Series

Set granularity to POWERSOF2 to restrict bucket boundaries to numbers that are a power of two.

Example:

The following numbers adhere to the power of two Series:

2^0 = 1
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
and so on…

A common implementation is how various computer components, like memory, often adhere to the POWERSOF2 set of preferred numbers:

1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, and so on….

https://docs.mongodb.com/manual/reference/operator/aggregation/bucketAuto/#granularity

Renard Series

E Series

1-2-5 Series

Powers of Two Series

Properties

Methods

Operators

Static Properties

mongo_aggregation library