# 51.26 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**

| <p>Column Type</p><p>Description</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><code>indexrelid</code> <code>oid</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-class.html"><code>pg\_class</code></a>.<code>oid</code>)</p><p>The OID of the <code>pg\_class</code> entry for this index</p>                                                                                                                                                                                                                                                                                                                                                                                              |
| <p><code>indrelid</code> <code>oid</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-class.html"><code>pg\_class</code></a>.<code>oid</code>)</p><p>The OID of the <code>pg\_class</code> entry for the table this index is for</p>                                                                                                                                                                                                                                                                                                                                                                               |
| <p><code>indnatts</code> <code>int2</code></p><p>The total number of columns in the index (duplicates <code>pg\_class.relnatts</code>); this number includes both key and included attributes</p>                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| <p><code>indnkeyatts</code> <code>int2</code></p><p>The number of <em>key columns</em> in the index, not counting any <em>included columns</em>, which are merely stored and do not participate in the index semantics</p>                                                                                                                                                                                                                                                                                                                                                                                                                |
| <p><code>indisunique</code> <code>bool</code></p><p>If true, this is a unique index</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| <p><code>indisprimary</code> <code>bool</code></p><p>If true, this index represents the primary key of the table (<code>indisunique</code> should always be true when this is true)</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| <p><code>indisexclusion</code> <code>bool</code></p><p>If true, this index supports an exclusion constraint</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| <p><code>indimmediate</code> <code>bool</code></p><p>If true, the uniqueness check is enforced immediately on insertion (irrelevant if <code>indisunique</code> is not true)</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| <p><code>indisclustered</code> <code>bool</code></p><p>If true, the table was last clustered on this index</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| <p><code>indisvalid</code> <code>bool</code></p><p>If true, the index is currently valid for queries. False means the index is possibly incomplete: it must still be modified by <code>INSERT</code>/<code>UPDATE</code> operations, but it cannot safely be used for queries. If it is unique, the uniqueness property is not guaranteed true either.</p>                                                                                                                                                                                                                                                                                |
| <p><code>indcheckxmin</code> <code>bool</code></p><p>If true, queries must not use the index until the <code>xmin</code> of this <code>pg\_index</code> row is below their <code>TransactionXmin</code> event horizon, because the table may contain broken HOT chains with incompatible rows that they can see</p>                                                                                                                                                                                                                                                                                                                       |
| <p><code>indisready</code> <code>bool</code></p><p>If true, the index is currently ready for inserts. False means the index must be ignored by <code>INSERT</code>/<code>UPDATE</code> operations.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| <p><code>indislive</code> <code>bool</code></p><p>If false, the index is in process of being dropped, and should be ignored for all purposes (including HOT-safety decisions)</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| <p><code>indisreplident</code> <code>bool</code></p><p>If true this index has been chosen as “replica identity” using <code>ALTER TABLE ... REPLICA IDENTITY USING INDEX ...</code></p>                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| <p><code>indkey</code> <code>int2vector</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-attribute.html"><code>pg\_attribute</code></a>.<code>attnum</code>)</p><p>This is an array of <code>indnatts</code> values that indicate which table columns this index indexes. For example a value of <code>1 3</code> 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.</p> |
| <p><code>indcollation</code> <code>oidvector</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-collation.html"><code>pg\_collation</code></a>.<code>oid</code>)</p><p>For each column in the index key (<code>indnkeyatts</code> 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.</p>                                                                                                                                                                                                                                                |
| <p><code>indclass</code> <code>oidvector</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-opclass.html"><code>pg\_opclass</code></a>.<code>oid</code>)</p><p>For each column in the index key (<code>indnkeyatts</code> values), this contains the OID of the operator class to use. See <a href="https://www.postgresql.org/docs/13/catalog-pg-opclass.html"><code>pg\_opclass</code></a> for details.</p>                                                                                                                                                                                                      |
| <p><code>indoption</code> <code>int2vector</code></p><p>This is an array of <code>indnkeyatts</code> values that store per-column flag bits. The meaning of the bits is defined by the index's access method.</p>                                                                                                                                                                                                                                                                                                                                                                                                                         |
| <p><code>indexprs</code> <code>pg\_node\_tree</code></p><p>Expression trees (in <code>nodeToString()</code> representation) for index attributes that are not simple column references. This is a list with one element for each zero entry in <code>indkey</code>. Null if all index attributes are simple references.</p>                                                                                                                                                                                                                                                                                                               |
| <p><code>indpred</code> <code>pg\_node\_tree</code></p><p>Expression tree (in <code>nodeToString()</code> representation) for partial index predicate. Null if not a partial index.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                   |


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