GreenPlum常用SQL

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);