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 the PG_CLASS entry for this index
indrelid	oid	OID of the PG_CLASS entry for the table that uses this index
indnatts	smallint	Number of columns in the index
indisunique	boolean	The index is unique if the value is true. The index is not unique if the value is false.
indisprimary	boolean	Primary key of the table if the value is true. indisunique should always be true when the value of this column is true. The index is not the primary key of the table if the value is false.
indisexclusion	boolean	This index supports exclusion constraints if the value is true. This index does not support exclusion constraints if the value is false.
indimmediate	boolean	A uniqueness check is performed upon data insertion if the value is true. A uniqueness check is not performed upon data insertion if the value is false.
indisclustered	boolean	The table was last clustered on this index if the value is true. The table was not clustered on this index if the value is false.
indisusable	boolean	This index supports INSERT/SELECT if the value is true. This index does not support INSERT/SELECT if the value is false.
indisvalid	boolean	This index is valid for queries if the value is true. If the value is false, the index is possibly incomplete and must still be modified by INSERT/UPDATE operations, but it cannot safely be used for queries. If it is a unique index, the uniqueness property is also not true.
indcheckxmin	boolean	If the value is true, queries must not use indexes until the xmin of this row in PG_INDEX is below their TransactionXmin, because the table may contain broken HOT chains with incompatible rows that they can see. If the value is false, queries can use indexes.
indisready	boolean	The index is available for inserted data if the value is true. Otherwise, this 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	ID of each column used by the index
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	If the value is true, the column of this index becomes the decoded column of logical decoding. If the value is false, the column of this index is not the 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.