PG_DATABASE
PG_DATABASE records information about available databases.
Table 1 PG_DATABASE columns
Name | Type | Description |
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oid | oid | Row identifier (hidden attribute, which must be specified) |
datname | name | Database name |
datdba | oid | Owner of the database, usually the user who created it |
encoding | integer | Character encoding for the database |
datcollate | name | Sequence used by the database |
datctype | name | Character type used by the database |
datistemplate | boolean | Whether the database can be used as a template database |
datallowconn | boolean | If the value is false, no one can connect to this database. This column is used to protect the template0 database from being altered. |
datconnlimit | integer | Maximum number of concurrent connections allowed on this database. The value –1 indicates no limit. |
datlastsysoid | oid | Last system OID in the database |
datfrozenxid | xid32 | Tracks whether the database needs to be vacuumed to prevent transaction ID wraparound. This column is discarded in the current version. To ensure forward compatibility, this column is reserved. The datfrozenxid64 column is added to record the information. |
dattablespace | oid | Default tablespace of the database |
datcompatibility | name | Database compatibility mode. Currently, four compatibility modes are supported: A, B, C, and PG, indicating that the Oracle, MySQL, Teradata, and Postgres databases are compatible. |
datacl | aclitem[] | Access permissions |
datfrozenxid64 | xid | Tracks whether the database needs to be vacuumed to prevent transaction ID wraparound. |
datminmxid | xid | All multi-transaction IDs before this one have been replaced with a transaction ID in the database. This is used to track whether the database needs to be vacuumed in order to prevent transaction IDs wraparound (or to allow pg_clog to be shrunk). It is the minimum pg_class.relminmxid value of all tables in the database. |
openGauss 2024-09-07 01:01:32