51.11. pg_class

oid oid

Row identifier

relname name

Name of the table, index, view, etc.

relnamespace oid (references pg_namespace . oid )

The OID of the namespace that contains this relation

reltype oid (references 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)

reloftype oid (references pg_type . oid )

For typed tables, the OID of the underlying composite type, zero for all other relations

relowner oid (references pg_authid . oid )

Owner of the relation

relam oid (references pg_am . oid )

If this is a table or an index, the access method used (heap, B-tree, hash, etc.)

relfilenode oid

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 (references 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 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 .

relallvisible 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 .

reltoastrelid oid (references 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.

relhasindex bool

True if this is a table and it has (or recently had) any 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.

relpersistence char

p = permanent table, u = unlogged table, t = temporary table

relkind 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 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

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 or index has (or once had) any inheritance children

relrowsecurity bool

True if table has row level security enabled; see pg_policy catalog

relforcerowsecurity bool

True if row level security (when enabled) will also apply to table owner; see pg_policy catalog

relispopulated bool

True if relation is populated (this is true for all relations other than some materialized views)

relreplident 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 bool

True if table or index is a partition

relrewrite oid (references pg_class . oid )

For new relations being written during a DDL operation that requires a table rewrite, this contains the OID of the original relation; otherwise 0. That state is only visible internally; this field should never contain anything other than 0 for a user-visible relation.

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_xact to be shrunk. Zero ( InvalidTransactionId ) if the relation is not a table.

relminmxid xid

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 5.7 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