PostgreSQL应用相关问题解决

PostgreSQL中是否区分聚簇索引与非聚簇索引的问题？

答：PostgreSQL中区分聚簇索引与非聚簇索引。

示例如下：

创建聚族索引:

CREATE INDEX test_ind

   ON yy (name ASC NULLS LAST);

ALTER TABLE yy

  CLUSTER ON test_ind;

创建非聚族索引:

CREATE INDEX test_uncluster_index

   ON yy (name ASC NULLS LAST);

临时表被删除，临时表的索引是否也被删除？

答：临时表被删除，临时表的索引也同时被删除。

示例如下：

创建两个临时表：
test1=# create temporary table tmp_t1(id int primary key,note text);
CREATE TABLE
test1=# dt
List of relations
Schema | Name | Type | Owner
----------------------+---------
pg_temp_2 | tmp_t1 | table | postgres
public | student | table | postgres
public | testdb | table | postgres
(3 rows)

test1=# create temporary table tmp_t2(id int primary key,name char(10),note text);
CREATE TABLE
test1=# dt
List of relations
Schema | Name | Type | Owner
----------------------+---------
pg_temp_2 | tmp_t1 | table | postgres
pg_temp_2 | tmp_t2 | table | postgres
public | student | table | postgres
public | testdb | table | postgres
(4 rows)
给两个临时表分别创建索引并查看索引：
test1=# create index idx_tmp_t1_id on tmp_t1(id);
CREATE INDEX
test1=# create index idx_tmp_t2_id on tmp_t2(id);
CREATE INDEX
test1=# di
List of relations
Schema | Name | Type | Owner | Table
-------------------------------------------
pg_temp_2 | idx_tmp_t1_id | index | postgres | tmp_t1
pg_temp_2 | idx_tmp_t2_id | index | postgres | tmp_t2
pg_temp_2 | tmp_t1_pkey | index | postgres | tmp_t1
pg_temp_2 | tmp_t2_pkey | index | postgres | tmp_t2
(4 rows)
删除临时表1：
test1=# drop table tmp_t1;
DROP TABLE
test1=# dt
List of relations
Schema | Name | Type | Owner
----------------------+---------
pg_temp_2 | tmp_t2 | table | postgres
public | student | table | postgres
public | testdb | table | postgres
(3 rows)
查看索引，临时表1的索引也被删除：
test1=# di
List of relations
Schema | Name | Type | Owner | Table
-------------------------------------------
pg_temp_2 | idx_tmp_t2_id | index | postgres | tmp_t2
pg_temp_2 | tmp_t2_pkey | index | postgres | tmp_t2
(2 rows)