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 the index.
indrelid	oid	OID of the PG_CLASS entry 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 check the uniqueness of data to be 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. For details, see section 12.2.15.53 PG_OPCLASS.
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.
indcctmpid	oid	OID of the temporary table when the Ustore builds indexes online.
indisvisible	Boolean	true: The index status is visible, that is, the optimizer can use the index. false: The index is invisible. If the value of enable_invisible_indexes is off, the optimizer cannot use the index. If the value of enable_invisible_indexes is on, the optimizer can use the index.