Postgresql 分区表测试

--创建父表

drop table  num_master;

create table num_master (id int not null primary key); 

--创建生成分区表的函数

create or replace function create_partition_table () returns void as $$

declare i int;

declare cnt int;

declare stmt text;

begin

i:= 0;

cnt:=4;

<<lable1>> while i < cnt loop

  stmt := 'create table num_slave'||i+1||'(check(id >='||i*100||' and id <'||(i+1)*100||')) inherits(num_master)';

  execute stmt;

  i:=i + 1;

end loop lable1;

return;

end;

$$ language plpgsql;

--执行分区表的创建

select create_partition_table ();

--创建触发器函数

create or replace function num_insert_trigger()

returns trigger as $$

begin

if (new.id >=0 and new.id <100) then

insert into num_slave1 values (new.*);

elsif (new.id >=100 and new.id <200) then

insert into num_slave2 values(new.*);

elsif (new.id >=200 and new.id <300) then

insert into num_slave3 values (new.*);

elsif (new.id >=300 and new.id <400) then

insert into num_slave4 values (new.*);

else

raise exception 'Column id out of range.';

end if;

return null;

end;

$$ language plpgsql;

--创建触发器

CREATE TRIGGER insert_num_master_trigger

BEFORE INSERT ON num_master 

FOR EACH ROW EXECUTE PROCEDURE num_insert_trigger();

test=# \d num_master

  Table "public.num_master"

 Column |  Type   | Modifiers 

--------+---------+-----------

 id     | integer | not null

Indexes:

    "num_master_pkey" PRIMARY KEY, btree (id)

Number of child tables: 4 (Use \d+ to list them.)

test=#  \d+ num_master

                      Table "public.num_master"

 Column |  Type   | Modifiers | Storage | Stats target | Description 

--------+---------+-----------+---------+--------------+-------------

 id     | integer | not null  | plain   |              | 

Indexes:

    "num_master_pkey" PRIMARY KEY, btree (id)

Triggers:

    insert_num_master_trigger BEFORE INSERT ON num_master FOR EACH ROW EXECUTE PROCEDURE num_insert_trigger()

Child tables: num_slave1,

              num_slave2,

              num_slave3,

              num_slave4

Has OIDs: no

--插入测试数据

\timing on

insert into num_master select id from (select generate_series(1,399))ids(id);

--查看测试的数据

test=# select count(*) from num_master;

 count 

-------

   399

(1 row)

Time: 0.577 ms

test=# select count(*) from num_slave1;

 count 

-------

    99

(1 row)

Time: 0.327 ms

test=# select count(*) from num_slave2;

 count 

-------

   100

(1 row)

Time: 0.304 ms

test=# select count(*) from num_slave3;

 count 

-------

   100

(1 row)

Time: 0.424 ms

test=# select count(*) from num_slave4;

 count 

-------

   100

(1 row)

--查看查询下优化器的选择

test=# explain select * from num_master where id > 30 and id < 120; 

                           QUERY PLAN                            

-----------------------------------------------------------------

 Append  (cost=0.00..4.98 rows=91 width=4)

   ->  Seq Scan on num_master  (cost=0.00..0.00 rows=1 width=4)

         Filter: ((id > 30) AND (id < 120))

   ->  Seq Scan on num_slave1  (cost=0.00..2.48 rows=70 width=4)

         Filter: ((id > 30) AND (id < 120))

   ->  Seq Scan on num_slave2  (cost=0.00..2.50 rows=20 width=4)

         Filter: ((id > 30) AND (id < 120))

(7 rows)

可以看到，选择了分区表进行查询