SYSTEM CATALOG · System catalog

pg_class

PostgreSQL documentation ↗Source definition ↗

The catalog pg_class describes tables and other objects that have columns or are otherwise similar to a table. This includes indexes (but see also pg_index), sequences (but see also pg_sequence), views, materialized views, composite types, and TOAST tables; see relkind. Below, when we mean all of these kinds of objects we speak of “relations”. Not all of pg_class's columns are meaningful for all relation kinds.

First seen PG 9.0Last seen PG 19Columns 34

9.0 9.1 9.2 9.3 9.4 9.5 9.6 10 11 12 13 14 15 16 17 18 19^β3

Checked column by column against a PostgreSQL 18.6 instance · Raw measurement record ↗

Columns PostgreSQL 18

pg_class

COLUMN	TYPE	DESCRIPTION
`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 relationReferences:`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 entryReferences:`pg_type.oid`
`reloftype`	`oid`NOT NULL	For typed tables, the OID of the underlying composite type; zero for all other relationsReferences:`pg_type.oid`
`relowner`	`oid`NOT NULL	Owner of the relationReferences:`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.References:`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.References:`pg_tablespace.oid`
`relpages`	`integer`NOT NULLDocumented as:`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`	`real`NOT NULLDocumented as:`float4`	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`	`integer`NOT NULLDocumented as:`int4`	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`	`integer`NOT NULLDocumented as:`int4`	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.References:`pg_class.oid`
`relhasindex`	`boolean`NOT NULLDocumented as:`bool`	True if this is a table and it has (or recently had) any indexes
`relisshared`	`boolean`NOT NULLDocumented as:`bool`	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 NULLDocumented as:`char`	p = permanent table/sequence, u = unlogged table/sequence, t = temporary table/sequence
`relkind`	`"char"`NOT NULLDocumented as:`char`	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`	`smallint`NOT NULLDocumented as:`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`	`smallint`NOT NULLDocumented as:`int2`	Number of CHECK constraints on the table; see pg_constraint catalog
`relhasrules`	`boolean`NOT NULLDocumented as:`bool`	True if table has (or once had) rules; see pg_rewrite catalog
`relhastriggers`	`boolean`NOT NULLDocumented as:`bool`	True if table has (or once had) triggers; see pg_trigger catalog
`relhassubclass`	`boolean`NOT NULLDocumented as:`bool`	True if table or index has (or once had) any inheritance children or partitions
`relrowsecurity`	`boolean`NOT NULLDocumented as:`bool`	True if table has row-level security enabled; see pg_policy catalog
`relforcerowsecurity`	`boolean`NOT NULLDocumented as:`bool`	True if row-level security (when enabled) will also apply to table owner; see pg_policy catalog
`relispopulated`	`boolean`NOT NULLDocumented as:`bool`	True if relation is populated (this is true for all relations other than some materialized views)
`relreplident`	`"char"`NOT NULLDocumented as:`char`	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`	`boolean`NOT NULLDocumented as:`bool`	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.References:`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

Columns marked "implicit" are not included in SELECT *; some early statistics views are completed from same-version source, and the extra provenance is shown in the column description.

Common system columns 6

System attributes PostgreSQL provides, normally not expanded by SELECT *. Kept separately so they are not mixed in with ordinary columns.

Columns	Type	attnum
`tableoid`	`oid`	-6
`cmax`	`cid`	-5
`xmax`	`xid`	-4
`cmin`	`cid`	-3
`xmin`	`xid`	-2
`ctid`	`tid`	-1

Column evolution matrix

Hover a cell for the column type

PresentAdded / type or attribute changeRemoved

COLUMN	9.0	9.1	9.2	9.3	9.4	9.5	9.6	10	11	12	13	14	15	16	17	18	19
`oid`
`relname`
`relnamespace`
`reltype`
`reloftype`
`relowner`
`relam`
`relfilenode`
`reltablespace`
`relpages`
`reltuples`
`reltoastrelid`
`reltoastidxid`					−	–	–	–	–	–	–	–	–	–	–	–	–
`relhasindex`
`relisshared`
`relistemp`		−	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–
`relkind`
`relnatts`
`relchecks`
`relhasoids`										−	–	–	–	–	–	–	–
`relhaspkey`									−	–	–	–	–	–	–	–	–
`relhasexclusion`		−	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–
`relhasrules`
`relhastriggers`
`relhassubclass`
`relfrozenxid`
`relacl`
`reloptions`
`relpersistence`	–
`relallvisible`	–	–
`relispopulated`	–	–	–
`relminmxid`	–	–	–
`relreplident`	–	–	–	–
`relrowsecurity`	–	–	–	–	–
`relforcerowsecurity`	–	–	–	–	–
`relispartition`	–	–	–	–	–	–	–
`relpartbound`	–	–	–	–	–	–	–
`relrewrite`	–	–	–	–	–	–	–	–
`relallfrozen`	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–

9.0 is the coverage baseline; a column already present in the baseline is not marked as added. The matrix aligns columns by name, so a rename appears as the old column removed and a new column added.

Evolution timeline

Changes between adjacent majors

PostgreSQL 19 ← 18

3 column description updates

PostgreSQL 18 ← 17

+ relallfrozen

PostgreSQL 17 ← 16

2 column description updates

PostgreSQL 15 ← 14

2 column description updates

PostgreSQL 14 ← 13

8 column description updates

PostgreSQL 12 ← 11

− relhasoids~ oid: implicit → ordinary5 column description updates

PostgreSQL 11 ← 10

+ relrewrite− relhaspkey3 column description updatesCatalog description updated

PostgreSQL 10 ← 9.6

+ relispartition+ relpartbound6 column description updatesCatalog description updated

PostgreSQL 9.5 ← 9.4

+ relrowsecurity+ relforcerowsecurity1 column description updates

PostgreSQL 9.4 ← 9.3

+ relreplident− reltoastidxid

PostgreSQL 9.3 ← 9.2

+ relispopulated+ relminmxid2 column description updatesCatalog description updated

PostgreSQL 9.2 ← 9.1

+ relallvisible

PostgreSQL 9.1 ← 9.0

+ relpersistence− relistemp− relhasexclusion1 column description updates

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FROMTOInclude description updates

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