STATE

SinceVersion 2.0.0

description

Syntax

AGGREGATE_FUNCTION_STATE(arg...) 返回聚合函数的中间结果，可以用于后续的聚合或者通过merge组合器获得实际计算结果，也可以直接写入agg_state类型的表保存下来。 结果的类型为agg_state，agg_state中的函数签名为AGGREGATE_FUNCTION(arg...)。

example

mysql [test]>select avg_merge(t) from (select avg_union(avg_state(1)) as t from d_table group by k1)p;
+----------------+
| avg_merge(`t`) |
+----------------+
|              1 |
+----------------+

keywords

AGG_STATE,STATE