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, sequences, and toast tables, 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.); otherwise zero (zero occurs for sequences, as well as relations without storage, such as views)

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. If the table has never yet been vacuumed or analyzed, reltuples contains -1 indicating that the row count is unknown.

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, zero 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;

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 zero. That state is only visible internally; this field should never contain anything other than zero 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;

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