Postgresql 中文操作指南

53.15. pg_database #

目录 pg_database 存储有关可用数据库的信息。可使用 CREATE DATABASE 命令创建数据库。参阅 Chapter 23 以了解有关某些参数含义的详细信息。

The catalog pg_database stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult Chapter 23 for details about the meaning of some of the parameters.

与大多数系统目录不同，pg_database 是集群的所有数据库共享的：每个集群只有一个 pg_database 的副本，而不是每个数据库一个。

Unlike most system catalogs, pg_database is shared across all databases of a cluster: there is only one copy of pg_database per cluster, not one per database.

Table 53.15. pg_database Columns

Column Type

Description

oid oid

Row identifier

datname name

Database name

datdba oid (references pg_authid.oid)

Owner of the database, usually the user who created it

encoding int4

Character encoding for this database (pg_encoding_to_char() can translate this number to the encoding name)

datlocprovider char

Locale provider for this database: c = libc, i = icu

datistemplate bool

If true, then this database can be cloned by any user with CREATEDB privileges; if false, then only superusers or the owner of the database can clone it.

datallowconn bool

If false then no one can connect to this database. This is used to protect the template0 database from being altered.

datconnlimit int4

Sets maximum number of concurrent connections that can be made to this database. -1 means no limit, -2 indicates the database is invalid.

datfrozenxid xid

All transaction IDs before this one have been replaced with a permanent (“frozen”) transaction ID in this database. This is used to track whether the database needs to be vacuumed in order to prevent transaction ID wraparound or to allow pg_xact to be shrunk. It is the minimum of the per-table pg_class.relfrozenxid values.

datminmxid xid

All multixact IDs before this one have been replaced with a transaction ID in this database. This is used to track whether the database needs to be vacuumed in order to prevent multixact ID wraparound or to allow pg_multixact to be shrunk. It is the minimum of the per-table pg_class.relminmxid values.

dattablespace oid (references pg_tablespace.oid)

The default tablespace for the database. Within this database, all tables for which pg_class.reltablespace is zero will be stored in this tablespace; in particular, all the non-shared system catalogs will be there.

datcollate text

LC_COLLATE for this database

datctype text

LC_CTYPE for this database

daticulocale text

ICU locale ID for this database

daticurules text

ICU collation rules for this database

datcollversion text

Provider-specific version of the collation. This is recorded when the database is created and then checked when it is used, to detect changes in the collation definition that could lead to data corruption.

datacl aclitem[]

Access privileges; see Section 5.7 for details