3.16. pg_index

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

Table 3-16. 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
indprocregprocpg_proc.oidThe function's OID if this is a functional index, else zero
indkeyint2vectorpg_attribute.attnum This is a vector (array) of up to INDEX_MAX_KEYS values that indicate which table columns this index pertains to. For example a value of 1 3 would mean that the first and the third column make up the index key. For a functional index, these columns are the inputs to the function, and the function's return value is the index key.
indclassoidvectorpg_opclass.oid For each column in the index key this contains a reference to the "operator class" to use. See pg_opclass for details.
indisclusteredbool If true, the table was last clustered on this index.
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.)
indreferenceoid unused
indpredtext Expression tree (in the form of a nodeToString representation) for partial index predicate. Empty string if not a partial index.