LINEAR_HISTOGRAM

Description

Syntax

LINEAR_HISTOGRAM(expr, DOUBLE interval[, DOUBLE offset)

The linear_histogram function is used to describe the distribution of the data, It uses an "equal width" bucking strategy, and divides the data into buckets according to the value of the data.

Parameter description:

• interval: Required. The bucket width.
• offset: Optional. Default is 0. It should be in [0, interval).

Example

mysql> select linear_histogram(a, 2) from histogram_test;
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| linear_histogram(a, cast(2 as DOUBLE))                                                                                                                                                                                                                                                                                                           |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| {"num_buckets":6,"buckets":[{"lower":0.0,"upper":2.0,"count":2,"acc_count":2},{"lower":2.0,"upper":4.0,"count":4,"acc_count":6},{"lower":4.0,"upper":6.0,"count":4,"acc_count":10},{"lower":6.0,"upper":8.0,"count":4,"acc_count":14},{"lower":8.0,"upper":10.0,"count":4,"acc_count":18},{"lower":10.0,"upper":12.0,"count":2,"acc_count":20}]} |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

mysql> select linear_histogram(a, 2, 1) from histogram_test;
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| linear_histogram(a, cast(2 as DOUBLE), cast(1 as DOUBLE))                                                                                                                                                                                                                                   |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| {"num_buckets":5,"buckets":[{"lower":1.0,"upper":3.0,"count":4,"acc_count":4},{"lower":3.0,"upper":5.0,"count":4,"acc_count":8},{"lower":5.0,"upper":7.0,"count":4,"acc_count":12},{"lower":7.0,"upper":9.0,"count":4,"acc_count":16},{"lower":9.0,"upper":11.0,"count":4,"acc_count":20}]} |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

Field description:

• num_buckets: The number of buckets.
• buckets: All buckets.
  • lower: Lower bound of the bucket. (included)
  • upper: Upper bound of the bucket. (not included)
  • count: The number of elements contained in the bucket.
  • acc_count: Accumulated count.

Keywords

LINEAR_HISTOGRAM