Description
Syntax
LINEAR_HISTOGRAM(expr, DOUBLE interval[, DOUBLE offset)
linear_histogram 函数用于描述数据分布情况，它使用“等宽”的分桶策略，并按照数据的值大小进行分桶。
参数说明：
interval：必须项。桶的宽度。offset：可选项。默认为 0，范围是[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}]} |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+字段说明：
num_buckets：桶的数量。buckets：直方图所包含的桶。lower：桶的下界。（包含在内）upper：桶的上界。（不包含在内）count：桶内包含的元素数量。acc_count：前面桶与当前桶元素的累计总量。
Keywords
LINEAR_HISTOGRAM