pg_class

The catalog pg_class describes tables and other objects that have columns or are otherwise similar to a table.

Reading PG 18current·documented in 24 of 24 versions, 7.4 to 20

7.4 8.0 8.1 8.2 8.3 8.4 9.0 9.1 9.2 9.3 9.4 9.5 9.6 10 11 12 13 14 15 16 17 18 19 20

Kind: System catalogs
Columns in this snapshot: 34
Definition source: English manual
Metadata snapshot: 18.6

Columns 34

As listed in the PostgreSQL 18 manual.

Column	Type	Description / reference
`oid`	`oid`NOT NULL	Row identifier
`relname`	`name`NOT NULL	Name of the table, index, view, etc.
`relnamespace`	`oid`NOT NULL	The OID of the namespace that contains this relation pg_namespace.oid
`reltype`	`oid`NOT NULL	The OID of the data type that corresponds to this table's row type, if any; zero for indexes, sequences, and toast tables, which have no pg_type entry pg_type.oid
`reloftype`	`oid`NOT NULL	For typed tables, the OID of the underlying composite type; zero for all other relations pg_type.oid
`relowner`	`oid`NOT NULL	Owner of the relation pg_authid.oid
`relam`	`oid`NOT NULL	The access method used to access this table or index. Not meaningful if the relation is a sequence or has no on-disk file, except for partitioned tables, where, if set, it takes precedence over default_table_access_method when determining the access method to use for partitions created when one is not specified in the creation command. pg_am.oid
`relfilenode`	`oid`NOT NULL	Name of the on-disk file of this relation; zero means this is a “mapped” relation whose disk file name is determined by low-level state
`reltablespace`	`oid`NOT NULL	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, except for partitioned tables, where this is the tablespace in which partitions will be created when one is not specified in the creation command. pg_tablespace.oid
`relpages`	`int4`NOT NULL	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`NOT NULL	Number of live 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. If the table has never yet been vacuumed or analyzed, reltuples contains -1 indicating that the row count is unknown.
`relallvisible`	`int4`NOT NULL	Number of pages that are marked all-visible in the table's visibility map. This is only an estimate used by the planner. It is updated by VACUUM, ANALYZE, and a few DDL commands such as CREATE INDEX.
`relallfrozen`	`int4`NOT NULL	Number of pages that are marked all-frozen in the table's visibility map. This is only an estimate used for triggering autovacuums. It can also be used along with relallvisible for scheduling manual vacuums and tuning vacuum's freezing behavior. It is updated by VACUUM, ANALYZE, and a few DDL commands such as CREATE INDEX.
`reltoastrelid`	`oid`NOT NULL	OID of the TOAST table associated with this table, zero if none. The TOAST table stores large attributes “out of line” in a secondary table. pg_class.oid
`relhasindex`	`bool`NOT NULL	True if this is a table and it has (or recently had) any indexes
`relisshared`	`bool`NOT NULL	True if this table is shared across all databases in the cluster. Only certain system catalogs (such as pg_database) are shared.
`relpersistence`	`char`NOT NULL	p = permanent table/sequence, u = unlogged table/sequence, t = temporary table/sequence
`relkind`	`char`NOT NULL	r = ordinary table, i = index, S = sequence, t = TOAST table, v = view, m = materialized view, c = composite type, f = foreign table, p = partitioned table, I = partitioned index
`relnatts`	`int2`NOT NULL	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`NOT NULL	Number of CHECK constraints on the table; see pg_constraint catalog
`relhasrules`	`bool`NOT NULL	True if table has (or once had) rules; see pg_rewrite catalog
`relhastriggers`	`bool`NOT NULL	True if table has (or once had) triggers; see pg_trigger catalog
`relhassubclass`	`bool`NOT NULL	True if table or index has (or once had) any inheritance children or partitions
`relrowsecurity`	`bool`NOT NULL	True if table has row-level security enabled; see pg_policy catalog
`relforcerowsecurity`	`bool`NOT NULL	True if row-level security (when enabled) will also apply to table owner; see pg_policy catalog
`relispopulated`	`bool`NOT NULL	True if relation is populated (this is true for all relations other than some materialized views)
`relreplident`	`char`NOT NULL	Columns used to form “replica identity” for rows: d = default (primary key, if any), n = nothing, f = all columns, i = index with indisreplident set (same as nothing if the index used has been dropped)
`relispartition`	`bool`NOT NULL	True if table or index is a partition
`relrewrite`	`oid`NOT NULL	For new relations being written during a DDL operation that requires a table rewrite, this contains the OID of the original relation; otherwise zero. That state is only visible internally; this field should never contain anything other than zero for a user-visible relation. pg_class.oid
`relfrozenxid`	`xid`NOT NULL	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_xact to be shrunk. Zero (InvalidTransactionId) if the relation is not a table.
`relminmxid`	`xid`NOT NULL	All multixact IDs before this one have been replaced by a transaction ID in this table. This is used to track whether the table needs to be vacuumed in order to prevent multixact ID wraparound or to allow pg_multixact to be shrunk. Zero (InvalidMultiXactId) if the relation is not a table.
`relacl`	`aclitem[]`	Access privileges; see Section 5.8 for details
`reloptions`	`text[]`	Access-method-specific options, as “keyword=value” strings
`relpartbound`	`pg_node_tree`	If table is a partition (see relispartition), internal representation of the partition bound