直至12版本,PostgreSQL仍沒有提供直接拆分分割槽的功能,暫時只能透過detach&attach實現,相對於Oracle的split支援,PG顯得比較的simple&naive.

**PG 12**
```
[pg12@localhost ~]$ psql -d testdb
Timing is on.
Expanded display is used automatically.
psql (12beta1)
Type "help" for help.

[local]:5432 pg12@testdb=# drop table t_p1;
) to (200);
create table t_p1_maxvalue partition of t_p1 for values from (200) to (maxvalue);

truncate table t_p1;
insert into t_p1(id,c1) values(1,1);
insert into t_p1(id,c1) values(2,100);
insert into t_p1(id,c1) values(3,125);
insert into t_p1(id,c1) values(4,200);
insert into t_p1(id,c1) values(5,250);
insert into t_p1(id,c1) values(6,300);
insert into t_p1(id,c1) values(7,350);
insert into t_p1(id,c1) values(8,4500);

alter table t_p1 detach partition t_p1_maxvalue;
create table t_p1_3 partition of t_ERROR:  table "t_p1" does not exist
Time: 8.497 ms
[local]:5432 pg12@testdb=# create table t_p1 (id int, c1 int) partition by range (c1);
p1 for values from (200) to (300);
insert into t_p1_3 select * from t_p1_maxvalue where c1 >= 200 and c1 < 300;
delete from t_p1_maxvalue where c1 >= 200 and c1 < 300;
alter table t_p1 attach partition t_p1_maxvalue for values from (300) to (maxvalue);CREATE TABLE
Time: 235.099 ms
[local]:5432 pg12@testdb=# create table t_p1_default partition of t_p1 default;
CREATE TABLE
Time: 11.941 ms
[local]:5432 pg12@testdb=# create table t_p1_1 partition of t_p1 for values from (1) to (100);
CREATE TABLE
Time: 15.247 ms
[local]:5432 pg12@testdb=# create table t_p1_2 partition of t_p1 for values from (100) to (200);
CREATE TABLE
Time: 1.705 ms
[local]:5432 pg12@testdb=# create table t_p1_maxvalue partition of t_p1 for values from (200) to (maxvalue);
CREATE TABLE
Time: 1.842 ms
[local]:5432 pg12@testdb=# 
[local]:5432 pg12@testdb=# truncate table t_p1;
TRUNCATE TABLE
Time: 3.413 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(1,1);
INSERT 0 1
Time: 1.152 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(2,100);
INSERT 0 1
Time: 0.871 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(3,125);
INSERT 0 1
Time: 0.487 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(4,200);
INSERT 0 1
Time: 0.949 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(5,250);
INSERT 0 1
Time: 0.494 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(6,300);
INSERT 0 1
Time: 0.463 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(7,350);
INSERT 0 1
Time: 0.481 ms
[local]:5432 pg12@testdb=# insert into t_p1(id,c1) values(8,4500);
INSERT 0 1
Time: 0.464 ms
[local]:5432 pg12@testdb=# 
[local]:5432 pg12@testdb=# alter table t_p1 detach partition t_p1_maxvalue;
ALTER TABLE
Time: 0.864 ms
[local]:5432 pg12@testdb=# create table t_p1_3 partition of t_p1 for values from (200) to (300);
CREATE TABLE
Time: 1.752 ms
[local]:5432 pg12@testdb=# insert into t_p1_3 select * from t_p1_maxvalue where c1 >= 200 and c1 < 300;
INSERT 0 2
Time: 7.578 ms
[local]:5432 pg12@testdb=# delete from t_p1_maxvalue where c1 >= 200 and c1 < 300;
DELETE 2
Time: 21.992 ms
[local]:5432 pg12@testdb=# alter table t_p1 attach partition t_p1_maxvalue for values from (300) to (maxvalue);
ALTER TABLE
Time: 7.356 ms
[local]:5432 pg12@testdb=# 
```

**Oracle**
```
TEST-orcl@DESKTOP-V430TU3>create table t_p1(id int,c1 int)
  2  partition by range(c1)
  3  (partition p1 values less than(100),
  4   partition p2 values less than(200),
  5   partition pmax values less than(maxvalue)
  6  );

Table created.

TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>truncate table t_p1;

Table truncated.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(1,1);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(2,100);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(3,125);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(4,200);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(5,250);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(6,300);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(7,350);

1 row created.

TEST-orcl@DESKTOP-V430TU3>insert into t_p1(id,c1) values(8,4500);

1 row created.

TEST-orcl@DESKTOP-V430TU3>alter table t_p1 split partition pmax at(1000) into (partition p3,partition pmx);

Table altered.

TEST-orcl@DESKTOP-V430TU3>
```

可以參照EDB的做法,加入此相容性.

**參考資料**
[13.3 Partitioning Commands Compatible with Oracle Databases](https://www.enterprisedb.com/edb-docs/d/edb-postgres-advanced-server/user-guides/database-compatibility-for-oracle-developers-guide/9.5/Database_Compatibility_for_Oracle_Developers_Guide.1.329.html#)

Oracle vs PostgreSQL DBA（13）- 拆分(split)分割槽

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