pg_index

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

columntypereferencesdescription
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 number of columns in the index (duplicates pg_class.relnatts).
indisuniqueboolean If true, this is a unique index.
indisprimaryboolean If true, this index represents the primary key of the table. (indisunique should always be true when this is true.)
indisclusteredboolean If true, the table was last clustered on this index via the CLUSTER command.
indisvalidboolean 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.
indkeyint2vectorpg_attribute.attnumThis 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 key. A zero in this array indicates that the corresponding index attribute is an expression over the table columns, rather than a simple column reference.
indclassoidvectorpg_opclass.oidFor each column in the index key this contains the OID of the operator class to use.
indexprstext 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.
indpredtext Expression tree (in nodeToString() representation) for partial index predicate. NULL if not a partial index.

Parent topic: System Catalogs Definitions