云数据库 GAUSSDB-分区表(母表)

时间:2024-11-13 10:04:55

分区表(母表)

实际对用户体现的表,用户对该表进行常规DML语句的增、删、查、改操作。通常使用在建表DDL语句显式的使用PARTITION BY语句进行定义,创建成功以后在pg_class表中新增一个entry,并且parttype列内容为'p',表明该entry为分区表的母表。分区母表通常是一个逻辑形态,对应的表文件并不存放数据。

示例:t1_hash为一个分区表,分区类型为hash:
gaussdb=# CREATE TABLE t1_hash (c1 INT, c2 INT, c3 INT)
PARTITION BY HASH(c1)
(
    PARTITION p0,
    PARTITION p1,
    PARTITION p2,
    PARTITION p3,
    PARTITION p4,
    PARTITION p5,
    PARTITION p6,
    PARTITION p7,
    PARTITION p8,
    PARTITION p9
);

gaussdb=# \d+ t1_hash
                      Table "public.t1_hash"
Column |  Type    | Modifiers | Storage | Stats target | Description
--------+---------+-----------+---------+--------------+-------------
c1     | integer |              | plain   |                 |
c2     | integer |              | plain   |                 |
c3     | integer |              | plain   |                 |
Partition By HASH(c1)
Number of partitions: 10 (View pg_partition to check each partition range.)
Distribute By: HASH(c1)
Location Nodes: ALL DATANODES
Has OIDs: no
Options: orientation=row, compression=no

--查询t1_hash分区类型。
gaussdb=#  SELECT relname, parttype FROM pg_class WHERE relname = 't1_hash';
relname | parttype
---------+----------
t1_hash | p           
(1 row)

--删除t1_hash。
gaussdb=# DROP TABLE t1_hash;
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