官方说法: work_mem (integer) Specifies the amount of memory to be used by internal sort operations and hash tables before writing to temporary disk files. The value defaults to four megabytes (4MB). Note that for a complex query, several sort or hash ope…
xmax The identity (transaction ID) of the deleting transaction, or zero for an undeleted row version. It is possible for this column to be nonzero in a visible row version. That usually indicates that the deleting transaction hasn't committed yet, or…
看官方文档: http://www.postgresql.org/docs/current/static/sql-prepare.html PREPARE creates a prepared statement. A prepared statement is a server-side object that can be used to optimize performance. When the PREPARE statement is executed, the specified s…
刚开始接触postgresql,安装后就有一个默认用户postgres,而且在启动postgresql后只能通过切换到linux的postgres用户才能登录数据库进行操作,和Mysql的登录认证居然不一样.查了好多资料才知道,原来有个pg_hba.conf的配置文件作登录限制.它的语法规则是这样的: local database user auth-method [auth-options] host database user address auth-method [auth-option…
1.继承的权限只是继承该组的表的权限,用户对应的管理员权限则不会被继承. 2.inherit权限是说本角色是否继承别人的权限,而不是本权限能否被别的角色继承. postgres=# create role test0 createdb createrole login; CREATE ROLE postgres=# \du List of roles Role name | Attributes | Member of -----------+------------------------…