CREATE OR REPLACE FUNCTION public.sfun_test1(

    results numeric[],

    val numeric)

    RETURNS numeric[]

    LANGUAGE 'plpgsql'

    COST 100

    VOLATILE

AS $BODY$

BEGIN

    results :=array_append(results,val);

RETURN results;

END;

$BODY$;

ALTER FUNCTION public.sfun_test1(numeric[], numeric)

    OWNER TO postgres;

CREATE OR REPLACE FUNCTION public.sffun_test1(

    results numeric[])

    RETURNS numeric

    LANGUAGE 'plpgsql'

    COST 100

    VOLATILE

AS $BODY$

DECLARE

    ppp integer;--百分位指标

    kkk numeric;--序号

    sss integer;--序号

    ret numeric[];--结果

BEGIN

    ppp=90;--第90百分位

    kkk=1+(array_length(results , 1)-1)*ppp/100::numeric;

    sss=floor(kkk);

    ret=array_sort(results,'asc');

RETURN ret[sss]+(ret[sss+1]-ret[sss])*(kkk-sss);

END;

$BODY$;

ALTER FUNCTION public.sffun_test1(numeric[])

    OWNER TO postgres;

CREATE AGGREGATE agg_test1(

BASETYPE = numeric,

SFUNC = sfun_test1,

STYPE = numeric[],

FINALFUNC = sffun_test1

);

CREATE AGGREGATE group_concat(anyelement)

(

  sfunc = array_append, -- 每行的操作函数，将本行append到数组里 

 stype = anyarray,  -- 聚集后返回数组类型 

   initcond = '{}'    -- 初始化空数组

);