51.26. pg_index

The catalog pg_index contains part of the information about indexes. The rest is mostly in pg_class.

Table 51.26. pg_index Columns

indexrelidoidpg_class.oidThe OID of the pg_class entry for this index
indrelidoidpg_class.oidThe OID of the pg_class entry for the table this index is for
indnattsint2 The total number of columns in the index (duplicates pg_class.relnatts); this number includes both key and included attributes
indnkeyattsint2 The number of key columns in the index, not counting any included columns, which are merely stored and do not participate in the index semantics
indisuniquebool If true, this is a unique index
indisprimarybool If true, this index represents the primary key of the table (indisunique should always be true when this is true)
indisexclusionbool If true, this index supports an exclusion constraint
indimmediatebool If true, the uniqueness check is enforced immediately on insertion (irrelevant if indisunique is not true)
indisclusteredbool If true, the table was last clustered on this index
indisvalidbool  If true, the index is currently valid for queries. False means the index is possibly incomplete: it must still be modified by INSERT/UPDATE operations, but it cannot safely be used for queries. If it is unique, the uniqueness property is not guaranteed true either.
indcheckxminbool  If true, queries must not use the index until the xmin of this pg_index row is below their TransactionXmin event horizon, because the table may contain broken HOT chains with incompatible rows that they can see
indisreadybool  If true, the index is currently ready for inserts. False means the index must be ignored by INSERT/UPDATE operations.
indislivebool  If false, the index is in process of being dropped, and should be ignored for all purposes (including HOT-safety decisions)
indisreplidentbool  If true this index has been chosen as replica identity using ALTER TABLE ... REPLICA IDENTITY USING INDEX ...
indkeyint2vectorpg_attribute.attnum This is an array of indnatts values that indicate which table columns this index indexes. For example a value of 1 3 would mean that the first and the third table columns make up the index entries. Key columns come before non-key (included) columns. A zero in this array indicates that the corresponding index attribute is an expression over the table columns, rather than a simple column reference.
indcollationoidvectorpg_collation.oid For each column in the index key (indnkeyatts values), this contains the OID of the collation to use for the index, or zero if the column is not of a collatable data type.
indclassoidvectorpg_opclass.oid For each column in the index key (indnkeyatts values), this contains the OID of the operator class to use. See pg_opclass for details.
indoptionint2vector  This is an array of indnkeyatts values that store per-column flag bits. The meaning of the bits is defined by the index's access method.
indexprspg_node_tree  Expression trees (in nodeToString() representation) for index attributes that are not simple column references. This is a list with one element for each zero entry in indkey. Null if all index attributes are simple references.
indpredpg_node_tree  Expression tree (in nodeToString() representation) for partial index predicate. Null if not a partial index.