会话级或事务级的临时表，临时表在会话结束或事物结束自动删除，任何在临时表上创建的索引也会被自动删除。除非用模式修饰的名字引用，否则现有的同名永久表在临时表存在期间，在本会话或事务中是不可见的。另外临时表对其他会话也是不可见的，但是会话级的临时表也可以使用临时表所在模式修饰的名字引用。 创建临时表的语法： CREATE TEMP tbl_name()ON COMMIT{PRESERVE ROWS|DELETE ROWS|DROP}; PRESERVE ROWS：默认值，事务提交...
使用 Django 框架代码能连上 PostgreSQL，但是在 pgAdmin 尝试连接这个表，却报错： ERROR: permission denied for table xxx 此时用 pgAdmin 连接其他的表是正常的，就这个表连不上。 先用 SELECT * FROM current_user 和 SELECT USER ，看一下目前 pgAdmin 登录的用户是哪个。 原来 pgAdmin 的连接用户与 Django 的连接使用的不是一个用户呀。 试了 GRANT ALL PRIVILEGED ON DATABASE yyy TO xxx，发现没用。 再试试 GRANT ALL P...
select * from pg_tablespace;spcname | spcowner | spclocation | spcacl ------------+----------+-------------------+---------------------pg_default | 10 | |pg_global | 10 | |adb | 2033793 | /database /adb | {adb =C/ adb}I can‘t see how, from the client, to get the path to where the global tablespace is stored; an empt...
示例1.create table tbl_inherits_parent( a int not null, b varchar(32) not null default ‘Got u‘, c int check (c > 0), d date not null );test=# alter table tbl_inherits_parent add constraint pk_tbl_inherits_parent_a primary key(a); ALTER TABLEtest=# alter table tbl_inherits_parent add constraint uk_tbl_inherits_parent_b_d unique (b,d); ALTER TABLEtest=# create table tbl_inherits_partition() inheri...
2. 插入数据 insert into tb10 select generate_series(1,5); 3. 把id的int变为varchar postgres=# alter table tb101 alter id type varchar; ALTER TABLE 因为int转varchar有隐式的转换，故可以自动转换过去。 postgres=# \d tb101Table "public.tb101"Column | Type | Modifiers --------+-------------------+-----------id | character varying | 4. 把id的varchar变为int postgres=# alter table tb...
1.下载 rpm知识库包操作系统版本：CentOS Linux release 7.2.1511 (Core) X64[root@localhost home]# yum install https://download.postgresql.org/pub/repos/yum/testing/10/redhat/rhel-7-x86_64/pgdg-centos10-10-1.noarch.rpm Preparing... ################################# [100%]Updating / installing... 1:pgdg-centos10-10-1 ################################# [100%]2.安装...
according to DocumentationVACUUM reclaims storage occupied by dead tuples. But according to this postDead rows are deleted rows that will later be reused for new rows from INSERTs or UPDATEs. Some dead rows (or reserved free space) can be particularly useful for HOT (Heap-Only Tuples) updates that can reuse space in the same data page efficientlypostgresql vacuum table标签：www. for some bod...
原文： https://www.postgresql.fastware.com/blog/how-postgresql-maps-your-tables-into-physical-files —————————————————————————————————— A few weeks back, I discussed how Transparent Data Encryption safeguards your data even in case an attacker gets hold of your files. So this week I would like to talk about how PostgreSQL maps database objects into actual files. Le...