1d9b3aeee7
The error format '##keyword' in a lot of docs. This pr is to repair document format. #4335
2.2 KiB
2.2 KiB
title, language
| title | language |
|---|---|
| PERCENTILE_APPROX | en |
PERCENTILE_APPROX
Description
Syntax
PERCENTILE_APPROX(expr, DOUBLE p[, DOUBLE compression])
Return the approximation of the point p, where the value of P is between 0 and 1.
Compression param is optional and can be setted to a value in the range of [2048, 10000]. The bigger compression you set, the more precise result and more time cost you will get. If it is not setted or not setted in the correct range, PERCENTILE_APPROX function will run with a default compression param of 10000.
This function uses fixed size memory, so less memory can be used for columns with high cardinality, and can be used to calculate statistics such as tp99.
example
MySQL > select `table`, percentile_approx(cost_time,0.99) from log_statis group by `table`;
+---------------------+---------------------------+
| table | percentile_approx(`cost_time`, 0.99) |
+----------+--------------------------------------+
| test | 54.22 |
+----------+--------------------------------------+
MySQL > select `table`, percentile_approx(cost_time,0.99, 4096) from log_statis group by `table`;
+---------------------+---------------------------+
| table | percentile_approx(`cost_time`, 0.99, 4096.0) |
+----------+--------------------------------------+
| test | 54.21 |
+----------+--------------------------------------+
keyword
PERCENTILE_APPROX,PERCENTILE,APPROX