pg_index
The catalog pg_index contains part of the information
about indexes. The rest is mostly in
pg_class.
Table 51.26. pg_index Columns
| Name | Type | References | Description |
|---|---|---|---|
indexrelid | oid | | The OID of the pg_class entry for this index |
indrelid | oid | | The OID of the pg_class entry for the table this index is for |
indnatts | int2 | The total number of columns in the index (duplicates
pg_class.relnatts); this number includes both key and included attributes | |
indnkeyatts | int2 | The number of key columns in the index, not counting any included columns, which are merely stored and do not participate in the index semantics | |
indisunique | bool | If true, this is a unique index | |
indisprimary | bool | If true, this index represents the primary key of the table
(indisunique should always be true when this is true) | |
indisexclusion | bool | If true, this index supports an exclusion constraint | |
indimmediate | bool | If true, the uniqueness check is enforced immediately on
insertion
(irrelevant if indisunique is not true) | |
indisclustered | bool | If true, the table was last clustered on this index | |
indisvalid | bool |
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. If it is unique, the uniqueness property is not
guaranteed true either.
| |
indcheckxmin | bool |
If true, queries must not use the index until the xmin
of this pg_index row is below their TransactionXmin
event horizon, because the table may contain broken HOT chains with
incompatible rows that they can see
| |
indisready | bool |
If true, the index is currently ready for inserts. False means the
index must be ignored by INSERT/UPDATE
operations.
| |
indislive | bool | If false, the index is in process of being dropped, and should be ignored for all purposes (including HOT-safety decisions) | |
indisreplident | bool |
If true this index has been chosen as “replica identity”
using ALTER TABLE ... REPLICA IDENTITY USING INDEX
...
| |
indkey | int2vector | |
This 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 entries. Key columns come before non-key
(included) columns. A zero in this array indicates that the
corresponding index attribute is an expression over the table columns,
rather than a simple column reference.
|
indcollation | oidvector | |
For each column in the index key
(indnkeyatts values), this contains the OID
of the collation to use for the index, or zero if the column is not of
a collatable data type.
|
indclass | oidvector | |
For each column in the index key
(indnkeyatts values), this contains the OID
of the operator class to use. See
pg_opclass for details.
|
indoption | int2vector |
This is an array of indnkeyatts 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. This is a list with one element for each zero
entry in indkey. Null if all index attributes
are simple references.
| |
indpred | pg_node_tree |
Expression tree (in nodeToString()
representation) for partial index predicate. Null if not a
partial index.
|