postgresql 所有聚合函數整理

SELECT DISTINCT(proname) FROM pg_proc WHERE proisagg order by proname 查所有

SELECT * FROM pg_proc WHERE proname like 'agg%' AND proisagg; 查所有agg開頭的

CREATE AGGREGATE agg_o3_8h(
BASETYPE = numeric,
SFUNC = sfun,
STYPE = numeric[],
FINALFUNC = sffun_o3_8h
);

CREATE AGGREGATE agg_percent90(
BASETYPE = numeric,
SFUNC = sfun,
STYPE = numeric[],
FINALFUNC = sffun_percent90
);

CREATE AGGREGATE agg_percent95(
BASETYPE = numeric,
SFUNC = sfun,
STYPE = numeric[],
FINALFUNC = sffun_percent95
);

字符串拼接聚合函數：
CREATE AGGREGATE agg_string_contact(anyelement)
(
sfunc = array_append, -- 每行的操作函數，將本行append到數組里
stype = anyarray, -- 聚集后返回數組類型
initcond = '{}' -- 初始化空數組

);

CREATE AGGREGATE group_concat(anyelement)
(
sfunc = array_append, -- 每行的操作函數，將本行append到數組里
stype = anyarray, -- 聚集后返回數組類型
initcond = '{}' -- 初始化空數組

);