pg_class PostgreSQL System Catalogs
select relname from pg_class;
select * from pg_class where relname like 'pg_class_%'
Структура и индексы таблицы pg_class
=# \d pg_class
Table "pg_catalog.pg_class"
Column | Type | Modifiers
----------------+-----------+-----------
relname | name | not null
relnamespace | oid | not null
reltype | oid | not null
relowner | oid | not null
relam | oid | not null
relfilenode | oid | not null
reltablespace | oid | not null
relpages | integer | not null
reltuples | real | not null
reltoastrelid | oid | not null
reltoastidxid | oid | not null
relhasindex | boolean | not null
relisshared | boolean | not null
relistemp | boolean | not null
relkind | "char" | not null
relnatts | smallint | not null
relchecks | smallint | not null
relhasoids | boolean | not null
relhaspkey | boolean | not null
relhasrules | boolean | not null
relhastriggers | boolean | not null
relhassubclass | boolean | not null
relfrozenxid | xid | not null
relacl | aclitem[] |
reloptions | text[] |
Indexes:
"pg_class_oid_index" UNIQUE, btree (oid)
"pg_class_relname_nsp_index" UNIQUE, btree (relname, relnamespace)
| Name | Type | References | Description | |
|---|---|---|---|---|
| relname | name | Name of the table, index, view, etc. | ||
| relnamespace | oid | pg_namespace.oid | The OID of the namespace that contains this relation | |
| reltype | oid | pg_type.oid | The OID of the data type that corresponds to this table's row type, if any (zero for indexes, which have no pg_type entry) | |
| relowner | oid | pg_authid.oid | Owner of the relation | |
| relam | oid | pg_am.oid | If this is an index, the access method used (B-tree, hash, etc.) | |
| relfilenode | oid | Name of the on-disk file of this relation; 0 if none | Имя файла на HDD; 0 если файл не существует | |
| reltablespace | oid | pg_tablespace.oid | The tablespace in which this relation is stored. If zero, the database's default tablespace is implied. (Not meaningful if the relation has no on-disk file.) | |
| relpages | int4 | Size of the on-disk representation of this table in pages (of size BLCKSZ). This is only an estimate used by the planner. It is updated by VACUUM, ANALYZE, and a few DDL commands such as CREATE INDEX | ||
| reltuples | float4 | Number of rows in the table. This is only an estimate used by the planner. It is updated by VACUUM, ANALYZE, and a few DDL commands such as CREATE INDEX | ||
| reltoastrelid | oid | pg_class.oid | OID of the TOAST table associated with this table, 0 if none. The TOAST table stores large attributes "out of line" in a secondary table | |
| reltoastidxid | oid | pg_class.oid | For a TOAST table, the OID of its index. 0 if not a TOAST table | |
| relhasindex | bool | True if this is a table and it has (or recently had) any indexes. This is set by CREATE INDEX, but not cleared immediately by DROP INDEX. VACUUM clears relhasindex if it finds the table has no indexes | ||
| relisshared | bool | True if this table is shared across all databases in the cluster. Only certain system catalogs (such as pg_database) are shared | ||
| relistemp | bool | True if this table is a temporary relation. If so, only the creating session can safely access its contents | ||
| relkind | char | r = ordinary table, i = index, S = sequence, v = view, c = composite type, t = TOAST table | ||
| relnatts | int2 | Number of user columns in the relation (system columns not counted). There must be this many corresponding entries in pg_attribute. See also pg_attribute.attnum | ||
| relchecks | int2 | Number of CHECK constraints on the table; see pg_constraint catalog | ||
| relhasoids | bool | True if we generate an OID for each row of the relation | ||
| relhaspkey | bool | True if the table has (or once had) a primary key | ||
| relhasrules | bool | True if table has (or once had) rules; see pg_rewrite catalog | ||
| relhastriggers | bool | True if table has (or once had) triggers; see pg_trigger catalog | ||
| relhassubclass | bool | True if table has (or once had) any inheritance children | ||
| relfrozenxid | xid | All transaction IDs before this one have been replaced with a permanent ("frozen") transaction ID in this table. This is used to track whether the table needs to be vacuumed in order to prevent transaction ID wraparound or to allow pg_clog to be shrunk. Zero (InvalidTransactionId) if the relation is not a table | ||
| relacl | aclitem[] | Access privileges; see GRANT and REVOKE for details | Привилегии доступа. | |
| reloptions | text[] | Access-method-specific options, as "keyword=value" strings | ||
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