> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/internals/system-catalogs/pg_statistic_ext.md).

# 51.50. pg\_statistic\_ext

版本：11

The catalog `pg_statistic_ext` holds definitions of extended planner statistics. Each row in this catalog corresponds to a *statistics object* created with [CREATE STATISTICS](https://www.postgresql.org/docs/13/sql-createstatistics.html).

#### **Table 51.50. `pg_statistic_ext` Columns**

| <p>Column Type</p><p>Description</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><code>oid</code> <code>oid</code></p><p>Row identifier</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| <p><code>stxrelid</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>Table containing the columns described by this object</p>                                                                                                                                                                                                                                                                                                                                            |
| <p><code>stxname</code> <code>name</code></p><p>Name of the statistics object</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| <p><code>stxnamespace</code> <code>oid</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-namespace.html"><code>pg\_namespace</code></a>.<code>oid</code>)</p><p>The OID of the namespace that contains this statistics object</p>                                                                                                                                                                                                                                                                                                                        |
| <p><code>stxowner</code> <code>oid</code> (references <a href="https://www.postgresql.org/docs/13/catalog-pg-authid.html"><code>pg\_authid</code></a>.<code>oid</code>)</p><p>Owner of the statistics object</p>                                                                                                                                                                                                                                                                                                                                                                 |
| <p><code>stxstattarget</code> <code>int4</code></p><p><code>stxstattarget</code> controls the level of detail of statistics accumulated for this statistics object by <a href="https://www.postgresql.org/docs/13/sql-analyze.html">ANALYZE</a>. A zero value indicates that no statistics should be collected. A negative value says to use the maximum of the statistics targets of the referenced columns, if set, or the system default statistics target. Positive values of <code>stxstattarget</code> determine the target number of “most common values” to collect.</p> |
| <p><code>stxkeys</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>An array of attribute numbers, indicating which table columns are covered by this statistics object; for example a value of <code>1 3</code> would mean that the first and the third table columns are covered</p>                                                                                                                                                                  |
| <p><code>stxkind</code> <code>char\[]</code></p><p>An array containing codes for the enabled statistic kinds; valid values are: <code>d</code> for n-distinct statistics, <code>f</code> for functional dependency statistics, and <code>m</code> for most common values (MCV) list statistics</p>                                                                                                                                                                                                                                                                               |

The `pg_statistic_ext` entry is filled in completely during `CREATE STATISTICS`, but the actual statistical values are not computed then. Subsequent `ANALYZE` commands compute the desired values and populate an entry in the [`pg_statistic_ext_data`](https://www.postgresql.org/docs/13/catalog-pg-statistic-ext-data.html) catalog.


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