PG_INDEX

PG_INDEX records part of index information. The rest is mostly recorded in PG_CLASS.

**Table 1** PG_INDEX columns
Name	Type	Description
indexrelid	oid	OID of 13.2.53 PG_CLASS for the index.
indrelid	oid	OID of 13.2.53 PG_CLASS for the table that uses the index.
indnatts	smallint	Number of columns in the index.
indisunique	Boolean	Specifies whether the index is unique. true: The index is unique. false: The index is not unique.
indisprimary	Boolean	Specifies whether the index is the primary key of the table. true: The index is the primary key of the table. indisunique should always be true when the value of this column is true. false: The index is not the primary key of the table.
indisexclusion	Boolean	Specifies whether the index supports exclusive constraints. true: The index supports exclusive constraints. false: The index does not support exclusive constraints.
indimmediate	Boolean	Specifies whether to perform the uniqueness check immediately when data is inserted true: The uniqueness check is performed immediately when data is inserted. false: The uniqueness check is not performed when data is inserted.
indisclustered	Boolean	Specifies whether the table is clustered on the index. true: The table is clustered on the index. false: The table is not clustered on the index.
indisusable	Boolean	Specifies whether the index is available for insert and select operations. true: The index is available for insert and select operations. false: The index is unavailable for insert and select operations.
indisvalid	Boolean	true: The index can be used for query. false: The index is possibly incomplete and must still be modified by INSERT or UPDATE operations, but it cannot be securely used for queries. If it is a unique index, the uniqueness property is also not true.
indcheckxmin	Boolean	true: Queries must not use the index until the xmin of this row in PG_INDEX is lower than their TransactionXmin, because the table may contain broken HOT chains with incompatible rows that they can see. false: Indexes can be used for query.
indisready	Boolean	true: The index is available for inserting data. false: The index is ignored when data is inserted or modified.
indkey	int2vector	This is an array of indnatts values indicating that this index creates table columns. For example, a value of 1 3 indicates that the first and the third columns make up the index key. The value 0 in this array indicates that the corresponding index attribute is an expression over the table columns, rather than a simple column reference.
indcollation	oidvector	OID of the collation corresponding to each index column. For details, see PG_COLLATION.
indclass	oidvector	For each column in the index key, this contains the OID of the operator class to use. See PG_OPCLASS for details.
indoption	int2vector	Array of values that store per-column flag bits. The meaning of the bits is defined by the index's access method.
indexprs	pg_node_tree	Expression trees (in nodeToString() representation) for index attributes that are not simple column references. It is a list with one element for each zero entry in indkey. The value is null if all index attributes are simple references.
indpred	pg_node_tree	Expression tree (in nodeToString() representation) for partial index predicate. If the index is not a partial index, this column is an empty string.
indisreplident	Boolean	Specifies whether the column of this index is a decoded column of logical decoding. true: The column of this index is a decoded column of logical decoding. false: The column of this index is not a decoded column of logical decoding.
indnkeyatts	smallint	Total number of columns in the index. The columns that exceed the value of indnatts are not involved in the index query.