下面整理记录一些时常会使用到的SQL,也方便以后查阅：

函数操作举例

例子一

删除函数：  DROP FUNCTION function_name(varchar);

创建函数：
CREATE OR REPLACE FUNCTION convert_grade(grade varchar)
  RETURNS integer AS
$BODY$  
DECLARE 
    result int; 
BEGIN 
    if grade = '优' then result = 1;
    ELSIF grade ='良' then  result = 2;
    ELSIF grade = '中' then  result = 3 ;
    ELSIF grade = '差' then  result = 4 ;
    end if ;
    RETURN result; 
END; 
$BODY$
  LANGUAGE plpgsql VOLATILE;

例子二

---------创建生成RADIUS表的函数,参数：省份的拼音------------------
CREATE OR REPLACE FUNCTION  CREATE_RADIUS_TABLE(province varchar)
RETURNS BOOLEAN AS $$
DECLARE
 passed BOOLEAN;
BEGIN
 EXECUTE
  'CREATE TABLE JK_'||province||'_RADIUS(
      ID bigserial,
     start_time BIGINT,
     end_time   BIGINT,
     user_account VARCHAR,
     src_ip     VARCHAR,
     bras       VARCHAR
     INSERT_DATE  DATE DEFAULT NOW()
    )DISTRIBUTED BY (ID)';
    EXECUTE 'ALTER SEQUENCE JK_'||province||'_RADIUS_ID_seq CACHE 100' ; 
    RETURN passed;
END;
$$  LANGUAGE plpgsql ;

----------用于创建所有省的所需的表-------------
CREATE OR REPLACE FUNCTION  CREATE_REPLACE_ALL_TABLE()
RETURNS BOOLEAN AS $$
DECLARE
 passed BOOLEAN:=TRUE;
 province varchar;
BEGIN

     FOR province IN
             SELECT OBJECT_EN_NAME FROM CM_PROVINCE
     LOOP
             EXECUTE 'DROP TABLE IF EXISTS JK_'||province||'_RADIUS'; --先删除
             PERFORM CREATE_RADIUS_TABLE(province);
      END LOOP;
      RETURN passed;
END;
$$  LANGUAGE plpgsql ;

例子三
CREATE OR REPLACE FUNCTION  CREATE_PARTITION(beginT timestamp with time zone,partitionN INTEGER)
RETURNS BOOLEAN AS $$
DECLARE
 passed BOOLEAN:=TRUE;
 pname VARCHAR ;
 smsc bigint ;
 emsc bigint ;
 beginTime timestamp with time zone;
 partitionNum INTEGER ;
BEGIN
 beginTime := to_TIMESTAMP(to_char(beginT,'yyyymmddhh34'),'yyyymmddhh34') ;
 partitionNum := partitionN;
        WHILE partitionNum > 0 LOOP
       
     --得到分区名称
     pname := to_char(beginTime,'yyyymmddhh34');
     --开始毫秒数
     smsc = extract(epoch from beginTime)::bigint * 1000;
     --结束毫秒
     beginTime := (beginTime + interval '1 hour');
     emsc = extract(epoch from beginTime)::bigint * 1000;
     --添加分区
     EXECUTE 'ALTER TABLE'||'JK_COMPLEX_XDR'||' SPLIT DEFAULT PARTITION START ('||smsc||') INCLUSIVE
     END ('||emsc||') EXCLUSIVE INTO (PARTITION p_day_'||pname||', default partition)';

     
     partitionNum := partitionNum-1;
     RAISE INFO 'current num: %,pname: %,stime:%,etime:%',partitionNum,pname,smsc,emsc;
     
    END LOOP;
        RETURN passed;
END;
$$  LANGUAGE plpgsql ;

例四：返回多条结果集
CREATE OR REPLACE FUNCTION  get_record()
RETURNS SETOF RECORD AS $$
DECLARE
       rec RECORD;
BEGIN
        FOR rec IN
             SELECT OBJECT_NAME FROM CM_PROVINCE
       LOOP
             RETURN NEXT rec;
        END LOOP;
        RETURN ;
END;
$$  LANGUAGE plpgsql ;

--执行函数
select * from get_record() t(name varchar) ;

添加两层分区举例
create table p_test(
    ID integer,
    name varchar ,
    time bigint
)DISTRIBUTED BY (ID)
PARTITION BY LIST(name)
SUBPARTITION BY RANGE(time)
SUBPARTITION TEMPLATE
(
 SUBPARTITION sp_time_111 START (BIGINT '111') INCLUSIVE END (BIGINT '222') EXCLUSIVE ,
 default SUBPARTITION sp_time_other
)
(
  PARTITION p_name_d VALUES('d'),
  PARTITION p_name_s VALUES('s'),
  PARTITION p_name_f VALUES('f')
);

--添加主分区
alter table p_test add partition p_name_x  VALUES('x');

--修改子分区模版,子分区将按照新的模版产生。已经存在的分区不会被修改
ALTER TABLE p_test SET SUBPARTITION TEMPLATE
(
 SUBPARTITION sp_time_222 START (BIGINT '222') INCLUSIVE END (BIGINT '333') EXCLUSIVE ,
 DEFAULT SUBPARTITION other
)

--查看分区情况
SELECT partitionboundary, partitiontablename,
        partitionname, partitionlevel, partitionrank
FROM pg_partitions WHERE tablename='p_test';

--查询指定的子分区
select * from p_test subpartition(sp_time_111);