参考文档：
http://postgres.cn/docs/11/sql-createtable.html
http://postgres.cn/docs/10/sql-createview.html

--- 基于会话的临时表（默认），会话结束，表消失
-- 会话1中创建临时表，在当前会话中查看该表 ，可以看到该表的schema为pg_temp_5，可以访问该表

create temporary table tmp_t1 (id int primary key,name text);
mydb=# create temporary table tmp_t1 (id int primary key,name text);
CREATE TABLE
mydb=# \d
               List of relations
  Schema   |      Name      | Type  |  Owner   
-----------+----------------+-------+----------
 pg_temp_5 | tmp_t1         | table | postgres
 public    | pg_buffercache | view  | postgres
 public    | pub_t1         | table | postgres
 public    | t              | table | postgres
(4 rows)
mydb=# 
mydb=# select * from pg_temp_5.tmp_t1;
 id | name 
----+------
(0 rows)
mydb=# 

-- 重新开一个会话，查看表，发现看不到该临时表 ，但是尝试加上schema，可以看到该表，尝试访问该表，不允许

mydb=# \d
             List of relations
 Schema |      Name      | Type  |  Owner   
--------+----------------+-------+----------
 public | pg_buffercache | view  | postgres
 public | pub_t1         | table | postgres
 public | t              | table | postgres
(3 rows)
mydb=# 
mydb=# \d pg_temp_5.tmp_t1
             Table "pg_temp_5.tmp_t1"
 Column |  Type   | Collation | Nullable | Default 
--------+---------+-----------+----------+---------
 id     | integer |           | not null | 
 name   | text    |           |          | 
Indexes:
    "tmp_t1_pkey" PRIMARY KEY, btree (id)
mydb=# 
mydb=# select * from pg_temp_5.tmp_t1;
ERROR:  cannot access temporary tables of other sessions
mydb=#

-- 在会话1中插入数据，会话2中仍然是查询不到数据的

insert into tmp_t1 values(1,'aaa'),(2,'bbb');
mydb=# insert into tmp_t1 values(1,'aaa'),(2,'bbb');
INSERT 0 2
mydb=# select * from tmp_t1;
 id | name 
----+------
  1 | aaa
  2 | bbb
(2 rows)
mydb=# 
mydb=# select * from pg_temp_5.tmp_t1;
ERROR:  cannot access temporary tables of other sessions
mydb=#

--测试，离开会话。可以看到，默认情况下，临时表是会话级别的。离开这个会话，再次连接数据库，发现这个表消失了

mydb=# \q
[root@test /root]$psql -d mydb
psql.bin (10.15)
Type "help" for help.
mydb=# \d
             List of relations
 Schema |      Name      | Type  |  Owner   
--------+----------------+-------+----------
 public | pg_buffercache | view  | postgres
 public | pub_t1         | table | postgres
 public | t              | table | postgres
(3 rows)
mydb=# 

-- 基于事务的临时表 ，事务结束，表还是存在的，但是表中数据不存在了

create temporary table tmp_t2 (id int primary key,name text) on commit delete rows;
insert into tmp_t2 values(1,'aaa'),(2,'bbb');  -- 如果这样，使用自动提交事务，则插入语句后，查询结果是0记录
mydb=# create temporary table tmp_t2 (id int primary key,name text) on commit delete rows;
CREATE TABLE
mydb=# \d
               List of relations
  Schema   |      Name      | Type  |  Owner   
-----------+----------------+-------+----------
 pg_temp_4 | tmp_t2         | table | postgres
 public    | pg_buffercache | view  | postgres
 public    | pub_t1         | table | postgres
 public    | t              | table | postgres
(4 rows)

-- 在事务中查看

begin ;
insert into tmp_t2 values(1,'aaa'),(2,'bbb');
select * from tmp_t2 ;
mydb=# begin ;
BEGIN
mydb=# select * from tmp_t2;
 id | name 
----+------
(0 rows)
mydb=# insert into tmp_t2 values(1,'aaa'),(2,'bbb');
INSERT 0 2
mydb=# select * from tmp_t2;
 id | name 
----+------
  1 | aaa
  2 | bbb
(2 rows)
mydb=# 

mydb=# \d pg_temp_4.tmp_t2   -- 在另一个会话中查看 ，可以看到表，但是不允许访问  
mydb=# \d pg_temp_4.tmp_t2
             Table "pg_temp_4.tmp_t2"
 Column |  Type   | Collation | Nullable | Default 
--------+---------+-----------+----------+---------
 id     | integer |           | not null | 
 name   | text    |           |          | 
Indexes:
    "tmp_t2_pkey" PRIMARY KEY, btree (id)
mydb=# select * from pg_temp_4.tmp_t2;
ERROR:  cannot access temporary tables of other sessions
mydb=# 

-- 结束事务，再次查看表，结果是事务结束，表中数据消失，表还存在 。

mydb=# commit;
COMMIT
mydb=# \d
               List of relations
  Schema   |      Name      | Type  |  Owner   
-----------+----------------+-------+----------
 pg_temp_4 | tmp_t2         | table | postgres
 public    | pg_buffercache | view  | postgres
 public    | pub_t1         | table | postgres
 public    | t              | table | postgres
(4 rows)
mydb=# select * from tmp_t2;
 id | name 
----+------
(0 rows)
mydb=# \d
               List of relations
  Schema   |      Name      | Type  |  Owner   
-----------+----------------+-------+----------
 pg_temp_4 | tmp_t2         | table | postgres
 public    | pg_buffercache | view  | postgres
 public    | pub_t1         | table | postgres
 public    | t              | table | postgres
(4 rows)
mydb=#  

-- 临时视图，当创建一个临时视图的时候，会话结束后，视图消失

create temp view v_pub_t1 as select * from pub_t1 where id <10;
select count(*) from v_pub_t1;
mydb=# create temp view v_pub_t1 as select * from pub_t1 where id <10;
CREATE VIEW
mydb=# \d v_pub_t1
                        View "pg_temp_5.v_pub_t1"
  Column  |            Type             | Collation | Nullable | Default 
----------+-----------------------------+-----------+----------+---------
 id       | integer                     |           |          | 
 name     | text                        |           |          | 
 crt_time | timestamp without time zone |           |          | 
\d: extra argument ";" ignored
mydb=# 
mydb=# select count(*) from v_pub_t1;
 count 
-------
(1 row)
mydb=# 
mydb=# \d
               List of relations
  Schema   |      Name      | Type  |  Owner   
-----------+----------------+-------+----------
 pg_temp_5 | v_pub_t1       | view  | postgres
 public    | pg_buffercache | view  | postgres
 public    | pub_t1         | table | postgres
 public    | t              | table | postgres
(4 rows)
mydb=# 

-- 在备库上能看到这个视图吗？经过测试，在备库上，是看不到这个视图的

-- 断开会话，再次查看，发现视图不见了

mydb=# \c mydb
You are now connected to database "mydb" as user "postgres".
mydb=# \d
             List of relations
 Schema |      Name      | Type  |  Owner   
--------+----------------+-------+----------
 public | pg_buffercache | view  | postgres
 public | pub_t1         | table | postgres
 public | t              | table | postgres
(3 rows)
mydb=#